Men's world No. 2 Daniil Medvedev has been pulled out of the upcoming Monte Carlo Masters and sent into isolation after testing positive for the coronavirus.
Medvedev, who was runner up to Novak Djokovic at the Australian Open earlier this year, had completed a practice session with Spain's Rafael Nadal prior to his positive test.
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Nadal has since returned a negative test, but his camp will wait for him to be tested again in three days for him to be given the all-clear.
Medvedev, who was seeded second behind top-ranked Novak Djokovic at the ATP Masters 1000 event on clay, has been put in isolation and is being monitored by the tournament and ATP medical teams, the men's tennis governing body said in a statement.
"It's a big disappointment not to play in Monte-Carlo," Medvedev said.
"My focus is now on recovery and I look forward to getting back out on Tour as soon and as safely as possible."
Nadal's publicist Benito Perez-Barbadillo told Reuters the the 34-year-old world No.3 was yet to show any symptoms but was being vigilant in watching for them.
"Nadal is absolutely fine," Perez-Barbadillo said on phone from Monte Carlo. "As we understand the virus does not anyways show before three-four days.
"The next scheduled testing is in three days."
Medvedev, who had a first round bye, was scheduled to play the winner of the match between Serbian Filip Krajinovic and Nikoloz Basilashvili of Georgia but tested positive on Monday.
The Russian was replaced in the draw by Argentinian lucky loser Juan Ignacio Londero while he was also withdrawn from doubles.
Alex Popyrin roars back after Monte Carlo 'bagel'
Alexei Popyrin demonstrated the sort of resilience his hero Lleyton Hewitt would have been proud of, battling back from a 6-0 first set drubbing to fight his way into the Monte Carlo Masters second round.
The 21-year-old Australian had looked all at sea on the red clay against Spanish grinder Pablo Andujar but eventually out-survived the man they call 'the Survivor' to win Tuesday's two-hour clash 0-6 6-2 7-6 (7-3).
Popyrin's resilient effort, which also saw him roar back from 3-0 down in the deciding tiebreak, ensured Australia will have three men in the last-32 at the Monte Carlo Country Club.
Jordan Thompson will meet the reigning champion Fabio Fognini, after the Italian beat Miomir Kecmanovic 6-2 7-5 on Tuesday, while John Millman tackles Chilean Cristian Garin, who beat the Toni Nadal-coached Felix Auger-Aliassime.
Popyrin's second-ever tour-level win on clay, though, took pride of place in Tuesday's action at the Monte Carlo Country Club.
He again showed he wasn't just paying lip service to his hero Hewitt when he said after his breakthrough Singapore Open triumph in February that he wanted to follow the former world No.1's never-say-die attitude.
Having had to make it through two qualifiers into the main draw, world No.83 Popyrin looked the novice on clay he still is, being completely outmanoeuvred by the 35-year-old veteran in the opening set.
Popyrin had only ever previously won one tour-level match on the red stuff and, with first serve misfiring badly and his firepower being scattered wildly, Andujar dished out a first-set 'bagel' in just 24 minutes.
Yet the attacking Popyrin took the first eight points of the second set as he raced into a 3-0 lead he never looked like relinquishing.
Getting his early-season game back to the level which saw him carve out an 11-4 record on hard courts this year, he saved four break points en route to taking the second set which he annexed with a glorious drop shot.
Putting Andujar on the back foot in the decider, 'Poppy' had a 3-1 lead which was pegged back, and also had a break point for a 5-3 advantage, only for the Spaniard to keep living up to his nickname.
In the tiebreak, Andujar's experience looked set to prevail but Popyrin played a blinder, reeling off six straight points before the Spaniard made it a calamitous seventh when serving a double at match point down.
Popyrin will next play Frenchman Lucas Pouille, who won a five-set thriller between the pair at the Australian Open two years ago.
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