The entire Chelsea first-team, coaching staff and several backroom members were ordered to self-isolate after it was confirmed on Friday Callum Hudson-Odoi had contracted coronavirus.
Hudson-Odoi, 19, was the first Premier League player to test positive for COVID-19.
But Mount was photographed playing five-a-side football with close friend and West Ham midfielder Declan Rice on Sunday.
Unlike Chelsea, West Ham have not implemented the same isolation procedures.
Stats Perform understands all of Chelsea's first-team players have since been reminded of their responsibilities.
Due to the pandemic, the Premier League has been put on hold until April 3.
However, many believe April is an unrealistic target with COVID-19 infections yet to peak in the United Kingdom.
Italy's Serie A is also postponed until April 3, though Italian Football Federation president Gabriele Gravina acknowledged that looks unlikely with the virus hitting the country hard.
Real Madrid playmaker Modric was influential as Croatia came from behind to beat Gareth Southgate's side 2-1 after extra time in the semi-finals of the 2018 World Cup.
A generation of exciting young talent will try to help England right that wrong at an expectant Wembley, with Chelsea star Mount one of the leading lights.
No Englishman created more goalscoring opportunities than the 22-year-old's 87 in the Premier League in 2020-21. Mount ended the top-flight campaign with six goals and five assists before laying on Kai Havertz's winner in the Champions League final against Manchester City.
Chelsea secured their place in the continental showpiece with a 3-1 aggregate semi-final win over Madrid, and Mount enlisted the help of club team-mate and Modric's international colleague Mateo Kovacic to secure a prized possession – the Ballon d'Or winner's shirt.
"Ever since he was in the Premier League with Tottenham, I have watched him quite closely," Mount said of Modric.
"Playing against him, it was weird because I had watched him so much. I kind of knew his moves and what he was going to do."
Speaking at a pre-match news conference, Modric reprised the row over Croatia's impression of English arrogance at Russia 2018 in the form of the "It's Coming Home" slogan – the chorus line from the Euro 96 song Three Lions, despite it largely being used in self-deprecation by England fans.
"That arrogance is not so much related to the players but the people around them, some of the journalists and commentators," he said.
PLAYERS TO WATCH
England – Raheem Sterling
Southgate looks set to keep faith with Sterling, who only scored one of his 14 Manchester City goals this season after the end of February. If he sees off the claims of Jadon Sancho and Jack Grealish for a starting berth, it will be because of his fine form in international colours. Since Russia 2018, no England player has scored more goals from open play than Sterling's 11.
Croatia – Ivan Perisic
Perisic netted the equaliser when the sides met in Moscow and tends to revel on the big stage. The experienced Inter winger is one of three European players to have either scored or assisted in the past for major tournaments since Euro 2012, alongside Andres Iniesta and Cristiano Ronaldo.
KEY OPTA FACTS
- England are taking part in their 10th European Championship finals – no team has played as many games in the tournament without ever reaching the final (31).
- Croatia have lost against the eventual winner in three of their past four major tournaments: Spain at Euro 2012, Portugal at Euro 2016 and France in the final of the 2018 World Cup.
- England have never won their opening game at a European Championship (D5 L4). Croatia, meanwhile, are unbeaten in their five Euro openers (W4 D1).
- Harry Kane was the top scorer in Euro 2020 qualifying, netting in every one of England's eight matches (12 goals), becoming the first player to do this in a single qualification campaign for the Three Lions.
- Since the start of 2019-20, only Zlatan Ibrahimovic (25) has scored more Serie A goals for Milan than Ante Rebic (22).
England sit bottom of Group 3 after Saturday's goalless draw at the Molineux Stadium, which was played behind closed doors after fan trouble during the Euro 2020 final between the two sides.
The Three Lions' only goal over these opening three games came via the penalty spot, with Harry Kane converting in the closing stages of their eventual 1-1 draw away to Germany.
According to Mount, the creation of chances would be more of an issue than their realisation but England still have to be able to capitalise after a second draw in three games.
"It is frustrating," he told Channel 4 post-match. "Obviously we want to win, we want to create chances and score goals. I probably should have done better with my chance, we had a few other chances, so it is something we need to look at.
"We have created chances but we should have done better with them. We are keeping clean sheets so it is something that is a positive but we need to keep working at it.
"We have had chances today and we probably should have scored, but sometimes you go through little periods where it is difficult. The only thing we can do is keep working hard in training, staying focused and look where we can improve. We have the players to do that, the talent and quality, just work at it."
Predominantly playing in an attacking three in Thomas Tuchel's 3-4-3 for Chelsea, Mount has seemingly found more freedom at international level as a conventional number 10.
Though deployed in a similar role to club level for their opening defeat to Hungary, England boss Gareth Southgate reverted to the 4-2-3-1, with the 23-year-old hinting he's more comfortable with the latter despite the result.
"I was in a 10 role so it gave me freedom to roam and find spaces, trying to link the midfield to the attacking boys," he said afterwards.
"I found myself in spaces to shoot a couple of time but did not to do well enough from my shot and it was too easy for the keeper. It is a difficult one to take because I feel we could have come away with more.
"We want to win every game, even if it is a friendly. We have looked at the last two games, felt confident in what we do but it is a tough one."
Mount and Chilwell are self-isolating for 10 days after coming into close contact with Billy Gilmour, their Chelsea team-mate who was man of the match for Scotland in their 0-0 draw with England at Wembley last Friday before testing positive for coronavirus.
The England duo have since returned negative PCR and lateral flow tests but are isolating in line with advice from Public Health England.
Gilmour has had to miss Scotland's decisive group clash with Croatia at Hampden Park on Tuesday, but no other member of Steve Clarke's squad has been ruled out despite their bubble being compromised, indicating none of the party have breached tournament protocols by being in sustained proximity to the 20-year-old midfielder.
Sky Sports reported that Gilmour, Chilwell and Mount spent 25 minutes in conversation in the Wembley tunnel after the match.
"I'm absolutely gutted to have to miss tonight’s game. I'll be cheering on the boys as usual and ensuring that I'm ready to go again when called upon. Come on @England!," Mount tweeted on Tuesday.
In a similar post, Chilwell said: "It's a tough one to take and I'm gutted but I want to wish the boys all the best tonight in the game, I'll be cheering you all on. I will make sure I am ready for when I can rejoin the squad. Lets go @England!"
Left-back Chilwell is yet to feature for England at Euro 2020, with Atletico Madrid's Kieran Trippier starting the tournament in the 1-0 win over Croatia before Manchester United's Luke Shaw was handed the position against Scotland.
Mount, by contrast, has established himself as an integral part of Gareth Southgate's plans, starting both games in an attacking midfield role.
He has had more shots than any England player (four), with the expected goals (xG) value of his attempts (0.66) second only to captain Harry Kane in the squad.
The Athletic has reported Southgate will satisfy a huge clamour for Jack Grealish by selecting the Aston Villa playmaker in Mount's absence, while Harry Maguire is set to make his first appearance of the tournament – replacing Tyrone Mings as John Stones' centre-back partner.
If England beat the Czech Republic, they will top Group D and play their last-16 game at Wembley next Tuesday, the day after Chilwell and Mount's stipulated period of self-isolation ends on June 28.
Although that would make both players' participation in that match doubtful, they would definitely be unavailable in the event of any draw or defeat against the Czechs that leaves Southgate's men as runners-up, as that would mean England face a knockout match at Parken Stadium in Copenhagan on Monday, June 28.
If England were to lose to the Czech Republic and a victory for either Croatia or Scotland resulted in enough of a goal-difference swing to leave Southgate's team third, Chilwell and Mount would have to wait and see which best-third place slot their team end up with, given England's last-16 match in that instance could take place on June 27 or June 29.
Sancho prevailed 2-1 despite initially trailing to a goal created by the in-game version of the Borussia Dortmund winger, his cross finding Rashford, controlled by Rashford.
"Oh, Jadon Sancho to Marcus Rashford! Sanch is under pressure right now," Rashford laughed on camera. "Oh my lord, I know you're sweating."
However, Sancho equalised through Rashford himself and then netted a winner with Raheem Sterling.
"I threw the game away, man," Rashford moaned, before adding: "You know what? I'm going to play you again. I'm going to go back to the drawing board and play you later."
Sixteen players across England's senior men's and women's teams and the Under-21s are involved in a tournament designed to raise awareness for staying at home during the coronavirus pandemic.
In the competition - which also highlighted the National Emergencies Trust, a collection of community foundations that distributes money to charities - Tammy Abraham, James Maddison, Todd Cantwell and Lucy Bronze were among the others to also advance to the quarter-finals.
Abraham was helped by a hat-trick from Rashford as he defeated Chelsea colleague Callum Hudson-Odoi 5-2.
Meanwhile, Maddison scored as himself in a come-from-behind 3-2 victory over Callum Wilson that was sealed with a winner from Harry Kane.
"Look who it is! The dangerman," Maddison cried after finding the net with his computerised self.
Cantwell won the battle of the midfielders against Mason Mount, with substitute Rashford scoring a hat-trick in a 5-0 win after the Norwich City man brought him off the bench.
Mount had threatened to quit if Cantwell scored with the virtual version of the Chelsea midfielder, though he vowed to retire from the game after the drubbing.
"Go and win this and I won't feel bad," he told Cantwell.
Cantwell's club team-mate Max Aarons had his own hat-trick hero as Maddison grabbed all the goals in the 3-1 victory over Trent Alexander-Arnold's England.
Elsewhere, Ryan Sessegnon won 3-1 against Reiss Nelson, who was in disbelief that it was only a one-game series, while a golden goal earned Bronze a victory over Ellie Roebuck.
Bronze is the only female representative in the last eight after Eddie Nketiah saw off fellow Arsenal star Jordan Nobbs, setting up a meeting with Sancho.
Rashford has scored 22 goals in all competitions this season, including a run of 14 strikes in 16 games.
Last off-season, United triggered a one-year option to prevent him becoming a free agent in June but interest in Rashford is ramping up amid his hot form.
TOP STORY – MAN UTD PLACE £120M PRICE ON RASHFORD
Manchester United have slapped a bumper £120 million price tag on in-form forward Marcus Rashford to ward off interest, claims The Daily Star.
Rashford, who is in the form of his life, has been the subject of reported interest from Paris Saint-Germain and Real Madrid.
Barcelona are also monitoring Rashford according to the report, with United are desperate to retain his services amid talk of a change of ownership at Old Trafford.
ROUND-UP
– Chelsea and Bayern Munich are among the clubs lining up to sign 19-year-old Atalanta defender Giorgio Scalvini who is valued at €40m according to Football Italia.
– Manchester City are set to reward Nathan Ake with a new contract offer, which represents a 50 per cent pay rise, according to the Daily Star. The Dutchman's weekly wages will rise from £80,000 to £120,000.
– Juventus will rival Liverpool in trying to sign Chelsea midfielder Mason Mount in the off-season, claims CalciomercatoWeb.
– Fichajes reports Tottenham are looking to sign Real Madrid defender Antonio Rudiger after this season.
– Newcastle United want to bolster their ranks by luring Juventus midfielder Adrien Rabiot, according to Fichajes. Rabiot's contract expires next season.
– Football Insider reports Liverpool are tracking 19-year-old Independiente defender Kevin Mantilla who impressed during the recent Under-20 South American Under-20 Championship with Colombia. The Reds have held preliminary talks with Mantilla.
Mac Allister, 24, is enjoying a career-best season, with his five goals in 17 Premier League fixtures already matching his best ever tally for a full league season.
The talented creative midfielder also made six starts for Argentina during their march to victory at the Qatar World Cup, scoring his first senior international goal during a 2-0 win over Poland in the group stage.
His emergence as a player capable of shining on the world stage, as well as his contribution to Brighton's terrific season, has apparently caught the eye of City boss Pep Guardiola.
TOP STORY – CITY VIEW MAC ALLISTER AS IDEAL GUNDOGAN REPLACEMENT
According to Fichajes, Gundogan is expected to leave City when his contract expires at the end of the season, and Bernardo Silva could follow if he gets his wish with a LaLiga move.
The report states Guardiola is a big fan of Mac Allister, and believes he has proven himself as a capable Premier League producer.
Fichajes claim Brighton have set an asking price in the range of £40million, indicating they are more willing to part ways with him than 21-year-old Moises Caicedo, with both of their contracts expiring in 2025.
ROUND-UP
– ESPN is reporting Napoli will hold firm with an asking price of at least €100m (£90m) for 24-year-old striker Victor Osimhen, who has strong interest from Manchester United and Paris Saint-Germain.
– According to 90min, Chelsea's top priority now is sorting out a contract extension for 24-year-old England international Mason Mount.
– Mason Greenwoodwill look to revive his career in Chinaif United decide to let him go, per the Sun.
– Caught Offside is reporting West Ham and Evertonwill have to return after the season if they want to sign 27-year-old winger Sheraldo Becker, with Union Berlin unwilling to deal in January due to their strong league position.
The United club captain is contracted until 2025 and his deal includes £200,000 per week wages.
Maguire has only started one of United's last eight Premier League games and did not play in Thursday's Europa League win over Real Betis.
TOP STORY – PSG SET FOR SHOCK MAGUIRE MOVE
Paris Saint-Germain are set for a shock £50million (€56m) move for Manchester United defender Harry Maguire, according to The Sun.
It has been claimed that Maguire is among a list of players that United are willing to sell in the off-season with Newcastle United and West Hamreportedly interested.
According to The Sun's report, PSG tabled a deal for Maguire in January, but time ran out to finalise it and the French champions will move again for him.
ROUND-UP
– The Independent reports Real Madrid are plotting an overhaul to bring in a new generation of young stars, with Manchester City's Erling Haaland top of the list along with Borussia Dortmund's Jude Bellingham.
– The Guardian reports Manchester United will enter the race to sign Chelsea midfielder Mason Mount, with interest also from Liverpool and Newcastle United. Mount and Chelsea are currently in the middle of a contract dispute, potentially making him available, with United viewing him as a cheaper alternative to Bellingham.
– Barcelona are in the market to sign Manchester City's Portuguese full-back Joao Canceloif Bayern Munich do not make permanent his loan spell, claims Sport.
– Newcastle are circling to sign Southampton free-kick specialist James Ward-Prowse, according to Football Insider. Newcastle are one of numerous Premier League clubs interested in him.
– Gazzetta dello Sport reports Inter have tabled a two-year contract offer to Edin Dzeko amid interest from West Ham.
– L'Equipe claims PSG are ramping up their bid to sign Manchester City midfielder Bernardo Silva in the off-season.
