Daniil Medvedev won a marathon match against Alexander Zverev to send Russia into the final of the ATP Cup for the first time.

The world number four and reigning ATP Finals champion triumphed 3-6 6-3 7-5 at Melbourne Park in a match lasting just under two hours and 40 minutes.

That result clinched victory over Germany in the semi-final after Andrey Rublev had earler fought back in style from a set down to defeat Jan-Lennard Struff 3-6 6-1 6-2.

"We're really happy to get the win, that's the most important [thing," Medvedev said. "Tough matches [for] both of us. Both [Andrey and I] lost the first set. [It was] not easy, because we had two days off before the match. But happy we're in the final. That's the most important."

Zverev appeared in control after breaking to go 3-2 ahead in the second set after winning the first, but Medvedev reeled off four games in a row as the world number seven began to struggle with a lower back problem.

"When it's against Sascha and you are 6-3, 3-2, break down, many times you're going to lose a match," Medvedev said. "But I needed to keep my chances alive for the team first of all, for the country. I just tried to stay there, got a bit tight maybe. I just did my job and I'm really happy about it."

Russia will meet Italy in the final following their defeat of Spain, which was secured by Matteo Berrettini's straight-sets win over Roberto Bautista Agut.

After Fabio Fognini saw off Pablo Carreno Busta in three sets, Berrettini - who has beaten three of the top 13 players in the world without dropping a set in this tournament - won 6-3 7-5 to set up Sunday's Russia showdown.

"It's an unbelievable feeling," said a delighted Berrettini, who was absent last year as Italy failed to progress from their group in the inaugural staging of the event. "Last year I couldn't make it, so I'm really happy that the first time that I played we are into the final.

"I'm feeling good. I'm feeling pumped. I'm feeling great to play not just for me, but for my team and for Italy in general. That's what matters the most. I'm really looking forward to playing tomorrow."

SINNER TO FACE FAMILIAR FOE

There will be an all-Italian affair in the final of the Great Ocean Road Open, with Jannik Sinner to face Stefano Travaglia.

In-form Sinner clinched an impressive 7-6 (7-4) 4-6 7-6 (7-4) win over second seed Karen Khachanov, in a three-hour battle, after his compatriot beat Thiago Monteiro 6-3 6-4.

At the Murray River Open, Felix Auger-Aliassime will meet Dan Evans in the final as each look to secure a first ATP Tour title.

Auger-Aliassime needed only 61 minutes to beat Corentin Moutet, while eighth seed Evans required a minute less to ease past Jeremy Chardy.

Novak Djokovic said it was "a tough one" to take after Serbia's hopes of retaining the ATP Cup title were ended by defeat to Germany.

The world number one scored a tense 6-7 (3-7) 6-2 7-5 victory over Alexander Zverev in their singles rubber, levelling the match after Jan-Lennard Struff beat Dusan Lajovic in three sets.

Zverev and Struff then teamed up in doubles to net a 7-6 (7-4) 5-7 10-7 win over Djokovic and Nikola Cacic.

The singles workout and win sets up the eight-time Australian Open champion well for the start of that grand slam next week, which was the consolation Djokovic could take from defeat.

Speaking about his singles clash with Zverev, Djokovic said: "It was anybody's game really. He was a set up, a couple points here and there in the beginning of the second. I just returned well when I needed to and closed out the match.

"It's never easy playing against Sascha [Zverev] when he's in form, and he's in really good form. We pushed each other to the very limit, and I'm glad that I had such a battle with him.

"It's unfortunate we lost the tie. That's what this competition is all about. It's about the team, not about winning one match, a singles match. Yeah, it's a tough one."

Germany advance to face Russia in the semi-finals on Saturday, with Daniil Medvedev and Andrey Rublev a formidable combination awaiting them.

Spain secured a shot at Italy in the second semi-final, despite a 2-1 defeat to Greece on Friday.

The Spanish team needed just one win in the group-stage match to advance, and that predictably came as Pablo Carreno Busta, ranked 16th by the ATP, beat world number 462 Michail Pervolarakis.

His 6-3 6-4 success could not be matched by team-mate Roberto Bautista Agut, who fell to a 7-5 7-5 defeat against Stefanos Tsitsipas, while Spain retired from the doubles rubber after one game, giving Greece a 2-1 success in the tie.

It remains to be seen whether Rafael Nadal will be fit to play any part in the semi-final, with the 20-time grand slam champion having been absent so far in the campaign due to a back injury.

"He's working very hard to recover his best feelings," said Spain captain Pepe Vendrell.

"Obviously he couldn't play any matches during the week. It's a situation that we have to study. But day by day he's improving. We will see [on Saturday] if he can play."

AWAY FROM THE ATP CUP, WAWRINKA ABANDONS

In the Murray River Open, Stan Wawrinka withdrew from his quarter-final with Jeremy Chardy after beating Australian Alex Bolt in a tough three-set match earlier in the day. Corentin Moutet, Dan Evans and Felix Auger-Aliassime joined Chardy in the last-four line-up.

Evans defeated Borna Coric, who had eliminated Australian hope Nick Kyrgios in his previous match.

All ATP and WTA tournaments are being played at Melbourne Park this week.

Thursday's play was cancelled due to a COVID-19 case affecting a worker from a hotel that accommodated quarantining players, and that meant Friday's schedule was packed.

The Great Ocean Road Open also saw players needing to win two matches in a day to reach the semi-finals, with Karen Khachanov, Thiago Monteiro and the Italian pair of Jannik Sinner and Stefano Travaglia coming through.

Daniil Medvedev and Andrey Rublev produced ruthless performances as Russia cruised into the ATP Cup semi-finals.

Russia followed up their day-one win over Argentina with victory against Japan to ensure they will finish top of Group D.

Rublev got things rolling with an emphatic 6-1 6-3 win over Yoshihito Nishioka and Medvedev dispatched Kei Nishikori in a 6-2 6-4 triumph.

Those results meant the subsequent doubles match – which Japan won – would not be relevant.

"I am really happy for the team," said ATP Finals champion Medvedev, who has now won 12 matches in a row on the tour.

"Reaching the semi-finals is a big step – I am really happy that we made it in both singles. Both matches were straight sets, so really happy for the team and hopefully we can go further than that."

Italy, who had beaten Austria on the opening day, are also through after Fabio Fognini and Matteo Berrettini earned wins in straight sets over France duo Benoit Paire and Gael Monfils on Wednesday.

France play Austria next but neither team can catch Italy in Group C.

Alexander Zverev won a thriller against Denis Shapovalov 6-7 (5-7) 6-3 7-6 (7-4) to ensure Germany defeated Canada.

It was a first win at the ATP Cup for US Open runner up Zverev, who had a miserable tournament in 2020.

That sets up a day three contest for Germany against Novak Djokovic and Serbia where the winning team will progress to face Russia.

KYRGIOS AND WAWRINKA THROUGH

Nick Kyrgios – playing his first tournament for a year – made it two wins from two at the Murray River Open, defeating fellow Australian Harry Bourchier 6-2 7-6 (9-7).

First seed Stan Wawrinka survived a scare before prevailing against Mikhail Kukushkin to win 4-6 6-3 6-1 in just under two hours.

Wawrinka will take on Alex Bolt in the last 16, while Kyrgios should be tested against fourth seed Borna Coric.

At the Great Ocean Road Open, top seed David Goffin crashed out as world number 146 Carlos Alcaraz celebrated a shock 6-3 6-3 victory.

Karen Khachanov and Jannik Sinner were among the seeds who progressed, both winning without dropping a set.

Novak Djokovic continued his perfect record at the ATP Cup to help Serbia beat Canada in their opening tie.

The world number one won all eight of his rubbers in the 2020 tournament and made a fine start to this event by battling to a 7-5 7-5 win over Denis Shapovalov in Melbourne.

Milos Raonic had earlier put Canada in front when he beat Dusan Lajovic 6-3 6-4, meaning Djokovic had to return for a decisive doubles clash alongside Filip Krajinovic. 

The Serbians prevailed, winning 7-5 7-6 (7-4) against Shapovalov and Raonic.

"Filip Krajinovic was the key," Djokovic said after the doubles triumph extended his undefeated run to 10. 

"The way he played is phenomenal. He came out with very solid returning. He found his serve, great rhythm. He just played some really key shots in the second set when we needed it the most."

Of his singles win, Djokovic added: "It was a very close match. Playing Shapo is always a great challenge on hard courts. 

"He's such a dynamic, explosive player; very talented. I thought we played on a very high level, so I'm really pleased with how I've started the season.

"This is the best way to kickstart the season, playing for your country.

"We don't get to see crowds in the tennis stadiums these days so much, so it's definitely a blessing. I'm really grateful to see you guys here in the stands."

SPAIN WIN WITHOUT NADAL

Defending champions Spain were without Rafael Nadal for their tie against Australia, but they still prevailed.

Pablo Carreno Busta had few problems seeing off John Millman 6-2 6-4.

And Roberto Bautista Agut ensured the tie was won before the doubles by emerging triumphant in an entertaining encounter with Alex de Minaur, which the Spaniard won 4-6 6-4 6-4.

Nadal, who is battling a back problem, hopes to return on Thursday when Spain take on Greece.

Elsewhere, Austria fell to a 2-1 loss against Italy, as US Open champion Dominic Thiem struggled.

After team-mate Dennis Novak had superbly beaten Fabio Fognini, world number three Thiem fell to a surprise 6-2 6-4 loss against Matteo Berrettini, with Austria going on to lose the decisive doubles.

Andrey Rublev and Daniil Medvedev beat Guido Pella and Diego Schwartzman respectively as Russia produced an impressive performance to beat Argentina.

Elsewhere, at the Murray River Open, Nick Kyrgios made a winning start to his comeback after a year out of action.

He did not have it easy against the unheralded Frenchman Alexandre Muller, but salvaged a 3-6 6-4 7-6 (7-4) victory to book a second-round meeting with fellow Australian Harry Bourchier.

Rafael Nadal wants to play at the Olympics but the star said fitting more quarantining into the ATP Tour calendar looked "difficult".

After being postponed last year due to the coronavirus pandemic, the Games are scheduled to start in Tokyo on July 23.

Naomi Osaka said she would be willing to quarantine ahead of the Olympics, with players having gone through similar in preparation for the Australian Open.

Nadal, an Olympic gold medallist in singles and doubles in 2008 and 2016 respectively, said he would listen to the experts, but acknowledged quarantining could be tough.

"It's the same as always. I am nobody to have a clear opinion on that.  I am just a tennis player, a human person that doesn't have enough knowledge about all the situation," the Spanish star told a news conference on Sunday.

"What we have to do is just follow the instructions of what the people who really have the right knowledge of all this stuff give to us. What's going to happen in Tokyo for the Olympics, if the Olympics are going to happen or not, or if we have to do quarantine before Olympics for 15 days or not, seems like a sports perspective very difficult because it's difficult for us, I don't know, combining our Tour with another 15 days of quarantine to play Olympics. It looks difficult to fix it in our calendar.

"But, as I said, we're going to do what the people who know about virus and who know about protecting the people in every single country, [we] are going to just follow their instructions."

Asked if his intention was to go, Nadal said: "I think everybody wants to play in Olympic Games, then let's see what's going on."

Nadal and Spain will begin their ATP Cup campaign against Australia on Tuesday.