The Blaugrana required an Ansu Fati winner in extra time to decide the seven-goal thriller against the third-tier opposition, which saw Oriol Soldevila net a remarkable hat-trick.
While the 31-time winners were able to respond in the right way, retaking the lead on three occasions after seeing the hosts equalise, Xavi is aware that there is plenty to improve ahead of a crunch LaLiga tie against Atletico Madrid this weekend.
"We conceded a lot in a game that we had very much under control," he told a post-match press conference. "We haven't blocked centres, we haven't defended the area well.
"We can't leave happy. The game has been pretty good, but we have to be more forceful. In defence it can happen, but the game had to be finished and there has been a lack of forcefulness.
"But we had to dominate the game, and we were good in the rhythm. We have interesting things, but we have suffered a lot. We've gotten too complicated.
"Today I'm happy with the game. We are lacking forcefulness. But we are in a good moment of play. I have to think about what we can improve."
Barcelona will discover their last-16 opponents in Friday's draw, with the tie to be played following the LaLiga clashes against Atletico and the Supercopa tie against Real Betis in Saudi Arabia.
Barca claimed a smash-and-grab victory at the Santiago Bernabeu on Thursday to take a slender advantage into next month's return game at Camp Nou.
The decisive goal came in the 26th minute when Franck Kessie's shot was saved by Thibaut Courtois before going in off Eder Militao.
Madrid were largely dominant otherwise, with Barca having just 35.3 per cent of the possession – that is their smallest share of the ball in a single match since Opta records began (2013-14 season).
Similarly, it was only the third time since the start of last year that Barca have recorded less than 50 per cent possession in a match.
Ancelotti was unimpressed by Barca's performance and remains confident Madrid will reach the final, despite Los Blancos failing to get a single shot on target for only the third time in a decade.
"The team played well," he told reporters. "Barcelona played like they didn't want to play.
"We haven't been good in the last third. Defeat hurts, but if we do the same in the second leg, we have a chance to progress.
"We played the game we have to play: pressing, playing with intensity. We lacked a goal, but they did nothing to score. They were lucky with a rebound. We have 90 minutes [to turn it around]."
He added: "We've failed, but we did not deserve to lose. But in 90 minutes we can score a goal in Barcelona."
Despite the obvious frustration in his voice, Ancelotti was undoubtedly impressed with how Madrid managed to control the majority of the game, forcing Barca to play mostly on the edge of their own box.
"It's a very bad result, undeserved, but it was a game well done on our part, with intensity and commitment.
"We didn't let Barca play the way they want. They had a very low block, not because they wanted to, but because we made them do it.
"It was difficult to have opportunities, we tried from outside the box, but they have great defenders and they gave us problems in the crosses.
"It was difficult to find spaces. They were very closed off. I have nothing to reproach. I am very happy and I am very excited to do the same in the second leg.
"They have an advantage, but we have all the confidence in the world to be able [to turn it around]."
The second leg is at Camp Nou on April 5.
Plying their trade in the Segunda Federacion, Cacereno more than held their own as the the European and LaLiga champions were unconvincing with Carlo Ancelotti having made nine alterations following the victory over Real Valladolid on Friday.
But in the 69th minute, Rodrygo jinked onto his right foot before arrowing into the top-right corner and that proved be enough to see Madrid through.
Madrid's hopes of winning a 20th Copa del Rey, and their first since the 2013-14 campaign, remain alive but they made hard work of the victory.
It took until the 16th minute for the first shot on target of the contest, Dani Ceballos sending a tame long-range effort into the waiting hands of Ivan Moreno in the Cacereno goal.
The underdogs largely kept their opponents at bay during the first half and had a couple of attempts of their own, with David Grande testing Andriy Lunin before Carmelo Merenciano saw a shot deflected over the crossbar.
Ancelotti made a pair of changes at the break, but they had little impact as Cacereno continued to look the more threatening of the two teams, though Marco Asensio stung the palms of Moreno with a fierce drive.
Madrid were in need of a moment of quality, and Rodrygo provided one it in abundance when a mazy run into the box ended with the forward superbly curling home.
Ancelotti's men would not relinquish that lead, despite some late pressure, and they are in the hat for the next round.
The World Health Organisation (WHO) officially declared COVID-19 to be a pandemic and major American sports franchises were taking appropriate measures as European football was forced to react once more.
Sports governing bodies have also had their say, with events calendars becoming increasingly fluid.
Here are some of the latest events to be impacted.
In the United Statesthe Golden State Warriors have confirmed their game against Brooklyn Nets on Thursday will be played behind closed doors, making them the first NBA team to make such a move following consultation with the City and County of San Francisco.
This directive also means the San Francisco Giants is working with Major League Baseball to make alternative arrangements after the planned March 24 exhibition game against the Oakland Athletics at Oracle Park was cancelled.
Seattle Mariners are hoping to relocate their opening games of the MLB regular season after Washington governor Jay Inslee announced large group events in the state would be banned throughout March.
The National Collegiate Athletic Association (NCAA) will stage its flagship March Madness basketball tournament "with only essential staff and limited family attendance".
Coronavirus cases in Spain have spiked, and the Royal Spanish Football Federation (RFEF) has postponed the Copa del Rey final between Real Sociedad and Athletic Bilbao.
The showpiece fixture was due to take place in Seville on April, with reports suggesting May 30 has been pencilled as a new date.
Barcelona have cancelled training sessions at their La Masia headquarters for the next 15 days, while RFEF has recommended football at all levels beneath the top two professional leagues is called off for two weeks.
In Germany, Eintracht Frankfurt announced Thursday's Europa League game against Basel will take place behind closed doors, while this weekend's derby between Hertha Berlin and Union Berlin will also take place without supporters.
Mainz's clash with Cologne is another of the forthcoming Bundesliga games where fans have been told to stay away.
The Premier League match between Manchester City and Arsenal became the first football match in Englandto be postponed as a coronavirus precaution and City are offering refunds on tickets to future fixtures up to and including the day of the game, acknowledging unease among supporters over taking part in large gatherings at this time.
Pep Guardiola's side have matches at home to Burnley and Real Madrid over the coming week.
CONMEBOL, the governing body for football in South America announced Copa Libertadores and Copa Sudamericana matches held in Paraguay will take place behind closed doors, in line with local government advice.
Qatar, which will host the 2022 World Cup, will stage all remaining matches in its domestic football season without supporters, although CAF has decided to maintain its competition schedule unless the WHO declares a country in Africa to be high risk.
The International Tennis Federation (ITF) has postponed the Fed Cup Finals in Budapest after Hungary's government prohibited public indoor gatherings of more than 100 people.
On their tour of Sri Lanka, the England cricket team have been told to avoid casual interaction with fans, such as selfies and autographs.
The veteran striker, who has scored 172 goals in over 400 appearances for Athletic, announced his intention to retire at the end of this season back in August.
His final season as a player is set to be marked by an all-Basque Copa del Rey final between Athletic and La Real.
Originally scheduled to take place on April 18 in Seville, the Copa showpiece - along with the vast majority of sport around the world - has been put on hold.
It is not clear when the final will be played. However, Aduriz accepts even an occasion as momentous as the clash with La Real has little significance amid a crisis that has killed over 12,000 people in Spain.
"This coronavirus crisis is forcing us to think twice and consider what matters," Aduriz told Athletic's official website. "And now my retirement, or football in general, or if we will play [the Copa del Rey final] or not doesn't matter.
"I think there are many other more important things to stop and solve. I'm sure with everyone's help together, with each of us playing our role, we will get ahead of it. That's what I'm focused on at this moment and that's the most important thing."
Aduriz was born in San Sebastian, where Real Sociedad hail from, but he expects a respectful reception from their fans if and when the final goes ahead.
He added: "Maybe all of us are keeping in mind the Copa del Rey final, but we're prioritising other things now.
"We're all going through a tough time where many people are struggling a lot and even passing away…so, the final of the Copa has its importance, but maybe not that much now.
"There are other things we need to solve together, and if the day [of the final] finally comes, I'm Donostiarra [people originally from San Sebastian]. I've always felt very comfortable in Donostia [the city's Basque name] and that won't change whatever happens in any football game. I'm sure they will treat me in the same way, no doubt."
Asked about recognition for his achievements from Athletic fans, Aduriz replied: "If we've learned something from this pandemic or virus that we're struggling with, it's that we should think twice about what is important.
"I sincerely believe the people who really deserve a statue and recognition are clear nowadays, and it's not me or any football player.
"I would build a statue to those who are battling every day at the very front line against the virus in all the hospitals. They're showing us what really matters.
"We have to realise what's important and what isn't. And this is probably showing us that football isn't important enough for this kind of recognition."
Basque sides Sociedad and Athletic were due to play for the trophy in Seville on April 18 but the match has been pushed back by the RFEF, Stats Perform understands
According to reports in the Spanish media, the game is set to be rescheduled for May 30.
At least the next two matchdays in Spain's top two tiers will be played behind closed doors due to the proliferation of COVID-19, though the national footballers' union has requested matches be suspended.
The RFEF also announced on Wednesday that all non-professional men's and women's football and futsal matches have been postponed for two weeks.
According to the World Health Organisation, Spain has seen 1,639 confirmed cases of coronavirus and 36 deaths.
Sport in Spain has been on hold since March due to the coronavirus pandemic and there is no date scheduled for the resumption of LaLiga or the postponed Copa final.
Clubs were granted permission to return to hold individual training sessions from Monday, provided strict protocols were followed.
Spanish prime minister Pedro Sanchez said on Saturday he was optimistic sport could return soon but it would likely be behind closed doors.
However, the Basque rivals will request that measure does not apply to their Copa final, which was initially scheduled to take place at Estadio de la Cartuja in Seville on April 18.
A joint-statement published by Athletic and La Real read: "The presidents of Real Sociedad and Athletic Club, both finalists of the Copa del Rey for the 2019-2020 season, after meeting with the president of the Royal Spanish Football Federation [RFEF], have agreed to ask RFEF for the final to be played with open doors, in public and in an official way, on a date to be determined and agreed between the three parties involved.
"The desire and will of both clubs has always been, now and before, to play and enjoy the final along with the supporters. This is what we would like most. A final to be lived with our supporters in the stands.
"At the same time, Real Sociedad and Athletic Club want the RFEF to guarantee that the final will be played as an official competition and will, therefore, be considered an official title.
"To this end, they have asked the general secretariat of the RFEF for the delegate committee of the RFEF General Assembly, whose next meeting will be held on Friday, to adopt a calendar amendment agreement that will enable the final to be held as an official title with the support and warmth of the fans of both teams.
"With this decision, Real Sociedad and Athletic Club wish to highlight one of the most prestigious and traditional sporting events that can be played around the world, unique in this edition, and to do so together with their fans, supporters, subscribers, members and partners, the true essence, and raison d’être of this wonderful sport."
Ronald Koeman's side won at this ground 4-0 in LaLiga last month but were facing a battle when Kenedy scored against the run of play after an error by Samuel Umtiti, making just his fifth start of the season.
Roberto Soldado struck a second on the break early in the second half and Barca struggled to get back into the contest against an exemplary Granada defence and inspired goalkeeper Aaron Escandell.
However, Griezmann turned in Lionel Messi's cross from deep with two minutes of normal time left and the same combination set up Jordi Alba to head in an injury-time equaliser.
Griezmann's fine header put Barca ahead in extra time but Fede Vico struck back straight away from the penalty spot, only for Frenkie de Jong and Alba again to settle the encounter at last.
Aaron was forced into six saves in the first half as Barca dominated proceedings, with a double stop to deny Messi and Francisco Trincao the pick of them.
It was Barca's own slack play that gifted Granada the lead, as some loose passing in defence ended in Umtiti being dispossessed by Alberto Soro, who teed up Kenedy for a tap-in.
Granada delivered a sucker-punch in the first two minutes of the second half. Angel Montoro intercepted a Griezmann pass and launched a long ball forward to Soldado, who raced away from Umtiti and slotted past Marc-Andre ter Stegen.
Trincao, Ousmane Dembele and Messi all hit the woodwork and Griezmann was denied from an overhead kick by a brilliant Aaron save, but the France forward turned a Messi cross in off post and keeper to give his side a lifeline.
The same Messi pass and Griezmann run teed up Alba to net an unlikely header, but Luis Suarez almost snatched a win for Granada with seconds left, the substitute dragging a shot wide after racing through on goal.
Aaron could do nothing to deny Griezmann's emphatic second in extra time as he rose highest to head in Alba's cross, but Vico restored parity three minutes later from the spot after Carlos Neva won a soft penalty from Sergino Dest.
But De Jong denied Granada a second semi-final in succession, side-footing into the net after Aaron had parried Messi's shot in the 109th minute, and Alba blasted home a stunning volley from Griezmann's clever pass to make certain the contest was over.
Griezmann had become a source of frustration for Barcelona fans during his two-year spell at Camp Nou, and also left many underwhelmed upon his return to Atletico in 2021.
He began look more influential during the first half of this season but a €40million purchase option centred around the number of minutes he played meant he was rarely a starter until Barca dropped their asking price and agreed a permanent sale to Atletico for €20m in October.
Griezmann then enjoyed a tremendous World Cup campaign with France despite featuring in a much deeper position, playing a vital role as Les Bleus made it all the way to the final before dramatically losing on penalties to Argentina.
Since returning to club action, he has tallied three assists in two matches, including a gorgeous first-time cushioned volley pass to set up Marcos Llorente in the 2-0 Copa del Rey defeat of second-tier Real Oviedo on Wednesday.
Simeone had always backed Griezmann, and he believes some of his critics are now being hushed.
"You have to go back and remember seven days before the World Cup, how he played in the first game [in the Copa del Rey] we had. He did it with the same dedication, the same commitment," Simeone told reporters.
"Antoine always wanted to be here. He regained the affection of the fans; [on] the field [he] speaks, and it is a good image for his teammates, wanting them to reach an important level.
"He is an extraordinary player despite the fact that many, many, thought otherwise."
Up next for Atletico on Sunday in LaLiga is the visit of Griezmann's former team, Barca.
A topsy-turvy tie saw the Blaugrana repeatedly frustrated by the minnows after Ronald Araujo's early effort had suggested a comfortable night for the 31-time winners.
That was certainly not the case, with Soldevila's hat-trick of equalisers sending the tie into extra time after Ousmane Dembele and Raphinha had each restored Barcelona's lead.
But Soldevila and Intercity could not repeat the feat a fourth time after Fati struck decisively in the 103rd minute.
A swift start for Xavi's side had seen Araujo head in Pablo Torre's corner with just four minutes on the clock, but the defender was soon required to clear off the line at the other end, and Intercity improved further after half-time.
A deserved equaliser followed just before the hour mark, with Vadik Murria nodding a corner down for Soldevila to fire past the helpless Inaki Pena.
The scores were only level for seven minutes as Dembele latched onto Gavi's pass to chip an effort over Gaizka Campos, but Intercity again fought back and Soldevila faced no challenge from Jordi Alba as he headed his second.
Alba redeemed himself with an assist for Raphinha at the other end, only for the winger to be brilliantly denied another by Campos, with Soldevila breaking from the subsequent corner to sensationally force extra time.
A fortuitous Barcelona fourth would prove enough, however, as Fati's deflected effort deceived Campos to send the visitors into the last 16.
The Spain international rifled home the second goal in Wednesday's routine 4-0 win over Real Zaragoza as Madrid cruised into the quarter-finals of the Copa del Rey.
Many have questioned Vazquez's role in the team, but he was praised by boss Zinedine Zidane for his display against Zaragoza and the winger is glad to have proved himself.
Asked how he reacts to the criticism directed his way, the 28-year-old told reporters: "I isolate myself from it. I'm a Madrid player and I know what I stand for.
"What you can't do is doubt yourself."
Madrid have gone 20 games without defeat in all competitions since losing 2-0 to Real Mallorca on October 19 and they lead the way by three points at the top of LaLiga.
Next up is a home match with city rivals Atletico Madrid on Saturday and Vazquez said: "The game in Mallorca was a turning point. It's brought good performances and good results.
"Playing [Atletico] is always difficult. They're not going to make things easy for us."
Raphael Varane, Vinicius Junior and Karim Benzema were also on target at the Estadio La Romareda as Madrid made it seven wins in a row.
Zidane's men remain on course for three more trophies, having already won the Supercopa de Espana earlier this month, and defender Dani Carvajal has set his sights on a clean sweep.
"We have three matches left [in the Copa] to be in the final and we are going for it," he said.
"We will take it step by step. On Saturday there's an important match - we want to keep this going. It's a special match."
Los Blancos were heading out at the Santiago Bernabeu after their former striker Alvaro Morata had struck in the first half for Atletico.
But Rodrygo's fantastic solo effort forced an extra half-hour in the Spanish capital, before Karim Benzema and Vinicius Junior completed the turnaround for the hosts.
Carlo Ancelotti's side join Barcelona, Athletic Bilbao and Osasuna in the semi-finals, but Diego Simeone's visitors will rue missing out on the last four.
Despite an early command of the game, it was the hosts who went behind in the 19th minute when Morata tapped in Nahuel Molina's square ball from close-range.
Madrid blew a big chance to level matters on the half-hour mark when Eder Militao was caught off-guard by a free-kick delivery and botched a simple header.
Matters went from bad to worse for Ancelotti's side too after they were forced into a substitution before the break thanks to an injury to Ferland Mendy.
Los Blancos were forced to wait for much of the game to find their response, but their patience paid off in the 79th minute when Rodrygo skipped past four Atletico players before prodding past Jan Oblak at his near post.
Tempers started to fray between both rivals in extra-time, with Stefan Savic dismissed in the 99th minute after two yellow cards in quick succession.
Gifted a man advantage, Madrid seized the chance with Benzema able to guide Vinicius' rushed effort in past Oblak, before the Brazilian signed off the game with a finish of his own, tucked away after a fine run in off the left wing.
The second-tier hosts arguably had the better opportunities, particularly in the first half, but Atletico were comfortable for much of the game as they avoided an upset.
Marcos Llorente landed the decisive blow in the first half after a period of Oviedo pressure, with Antoine Griezmann – who claimed two assists in the weekend win over Elche – brilliantly setting him up.
Atletico allowed Oviedo to enjoy plenty of possession after the break, but the visitors looked even more comfortable than before and finished the hosts off through substitute Pablo Barrios late on.
Alvaro Morata fired just wide and Llorente forced Tomeu Nadal into a necessary save as Atletico began with intent, but Oviedo soon settled and created chances of their own.
Samuel Obeng was their chief threat but put an inviting Hugo Rama cross into the side-netting from close range and volleyed over 12 yards out either side of Rodrigo Tarin drilling agonisingly past Jan Oblak's left-hand post.
Atletico capitalised in the 24th minute, Llorente getting a little lucky as his scuffed effort beat Nadal after Griezmann's gorgeous first-time pass – a cushioned volley – released him through on goal.
Borja Baston, an Atletico academy product, came on for Oviedo at half-time and saw an early effort fly just off target.
But the game was put beyond doubt seven minutes from time as Barrios – who also scored in the previous round – collected Angel Correa's well-weighted lay-off and finished through Nadal's legs.
Goals in each half from Adnan Januzaj and Alexander Sorloth saw Imanol Alguacil's team claim victory at Reale Arena.
Elimination from the Copa del Rey for Atletico came less than a week after their semi-final loss to Athletic Bilbao in the Supercopa de Espana in Saudi Arabia.
Diego Simeone tried to shake things up when he introduced the trio of Luis Suarez, Matheus Cunha and Thomas Lemar just 10 minutes into the second half, but it made little difference as the hosts saw out the win.
La Real dominated the opening period of the game and had two early chances with Aritz Elustondo heading wide when free at the far post before Januzaj saw an effort blocked and his follow-up strike the post.
Atletico hit the woodwork themselves with their first real chance after 15 minutes when a ball from Rodrigo de Paul found Yannick Carrasco, but the Belgian was thwarted by the near post.
The hosts had the lead in the 33rd minute when some nice interplay released Joseba Zaldua down the right and his cross found the head of Januzaj, who somehow rose above a sea of Atletico defenders to guide a header in off the left-hand upright.
It was 2-0 within two minutes of the restart after a mistake from Felipe allowed Mikel Oyarzabal to stab the ball through to Sorloth and he finished past Jan Oblak with ease.
Sorloth and Mikel Merino went close to extending the lead further but it proved inconsequential as La Real were rarely troubled at the other end.
Athletic knocked Barca out of the competition at the quarter-final stage last week thanks to a stoppage-time own goal from Sergio Busquets.
Madrid had earlier been defeated 4-3 at home by Athletic's Basque rivals Real Sociedad, marking the first time in 65 years that Spain's grandest two clubs had been eliminated from the Copa on the same day.
The semi-finals will see Athletic face Granada and Sociedad take on Mirandes, with the decision to reformat the competition by removing two-legged ties prior to the last four paying dividends for some of Spain's lesser lights.
Aduriz was part of the team beaten by Barca in the 2015 final, during the Catalans' run of winning the trophy in four consecutive years.
Indeed, Athletic have lost three Copa finals to Barca since 2009, and Aduriz is now eager to end his career by making the most of a more level playing field.
"[The new format] is not discredited; on the contrary, it has more value," said the striker at the Panenka magazine gala. "We are a little tired of seeing Barcelona and Real Madrid win everything.
"But it is nice to see competitions with more dynamism. You can see it in England, [where] it's enriching. It's a format that people like.
"I have been fantasising about [winning the cup] for a long time. At the beginning, it was a fantasy, and it may be closer now, although it is very difficult.
"Imagine retiring from football this season and winning a title. It's anyone's dream."
Aduriz also made it clear he is in favour of VAR, despite persistent criticism of the technology from across Europe's top leagues.
VAR has been criticised since its introduction, but Aduriz stressed he is in favour of the new technology.
"I love VAR," he said. "It is clear that we have to improve. It is new and it will evolve, but there is more success than the opposite.
"It makes me calmer on the pitch."
