Fernando Verdasco said he underwent "multiple" tests including in Rome and Hamburg, all of which were negative until he tested positive in Paris on Tuesday.
Rafael Nadal's bid for a 13th Paris title, and a record-equalling 20th Slam, and Novak Djokovic's pursuit of a second triumph in the French capital, to take him to 18 majors, are vying with health concerns in the battle for public attention.
The No. 1-ranked Djokovic began his bid for Grand Slam title No. 18 on Monday night by extending his season start to 24-0 with a 6-1, 6-4, 6-1 victory over Damir Dzumhur at Flushing Meadows.
US Open 2020: Novak Djokovic eases past Damir Dzumhur in first round; Alexander Zverev earns hard-fought win over Kevin Anderson
Alexander Zverev was made to work hard as he progressed into round two of the US Open Monday following a three-hour-long tussle with 2017 finalist Kevin Anderson.
Despite being bothered by neck stiffness at times, Djokovic showed he remains the man to beat in the Flushing Meadows fortnight as he challenges for tennis history.
US Open 2019: Hoping to resurrect after a heart-breaking Wimbledon loss, Roger Federer starts slow at Flushing Meadows
Over the years, Federer has shown just how good he is at dusting off wins and defeats – treating those two impostors just the same, as Rudyard Kipling would say. The biggest test will be how he resurrects in the face of his most heart-breaking loss.
US Open 2019: Novak Djokovic deals with pain, Roger Federer once again concedes deficit before win in rain-hit day
Novak Djokovic and Roger Federer, placed in the same half of the men's singles draw at US Open, had niggles and issues to deal with on their way to the third round.
US Open 2019: Roger Federer not concerned with sluggish start to tournament as he registers comeback win in first round
Roger Federer produced 19 unforced errors to surprisingly drop the first set against Sumit Nagal ranked 190th and without a tour-level win.
Marseille Open 13: Greek star Stefanos Tsitsipas enters quarter-finals with comfortable win over Hubert Hurkacz
Rising Greek star Stefanos Tsitsipas bounced back from successive defeats with a comfortable win over Poland's Hubert Hurkacz to reach the quarter-finals in Marseille on Wednesday.
Rotterdam Open: Kei Nishikori produces near-perfect performance against Marton Fucsovics to set up Stan Wawrinka semi-final
Kei Nishikori continued his unbeaten debut week at the Rotterdam Open with a 6-3, 6-2 defeat of Hungary's Marton Fucsovics on Friday to reach the semi-finals on the back of a performance he described as "almost perfect".
Rotterdam Open: Russian fifth-seed Daniil Medvedev ends Jo-Wilfried Tsonga's seven match win streak to enter semi-final
Daniil Medvedev outlasted 33-year-old Jo-Wilfried Tsonga in a 90-minute struggle to reach the semi-finals and a meeting with Gael Monfils in the Rotterdam Open.
Rotterdam Open: Jo-Wilfried Tsonga secures straight sets victory over Tallon Griekspoor to set up Daniil Medvedev clash
Tsonga's 7-6 (7/5), 6-1 victory was a match of two parts, with the labourious first set taking 53 minutes while the second lasted for just 23
Rotterdam Open: Stefanos Tsitsipas 'loses to himself' in shock last-16 exit; Stan Wawrinka downs Milos Raonic
Rising Greek star Stefanos Tsitsipas said he "lost to himself" after suffering a shock defeat at the ATP event in Rotterdam by Bosnian Damir Dzumhur on Wednesday.
Qatar Open: World No. 1 Novak Djokovic pulls off comeback victory against Marton Fucsovics to enter quarter-finals
A backhand winner eventually secured victory for Djokovic but the result was in doubt for a long time, with the Serb only breaking Fucsovics in the tenth game of the second set
Qatar Open: Novak Djokovic cruises past Damir Dzumhur in opening round; Dominic Thiem suffers shock defeat
Novak Djokovic took just 55 minutes to claim his first win of 2019, brushing aside Damir Dzumhur 6-1, 6-2 in the Qatar Open first round on Tuesday.
Paris Masters: Novak Djokovic reaches new personal landmark in win over injured Damir Dzumhur in pre-quarters
Novak Djokovic celebrated his elevation to world number one by reaching a new personal landmark to reach the Paris Masters quarter-finals on Thursday.
Paris Masters: In-form Novak Djokovic outsmarts Joao Sousa in tournament opener; Roger Federer confirms participation
Novak Djokovic stepped up his pursuit of the world number one ranking with a 7-5, 6-1 win over Joao Sousa at the Paris Masters on Tuesday, while Roger Federer confirmed he will play at the event for the first time since 2015.
Shenzhen Open: Andy Murray loses to Fernando Verdasco in quarters; teenager Yoshihito Nishioka advances
Britain's former world number one Andy Murray had his hopes of a second ATP Shenzhen Open title dashed on Friday night as Spanish veteran Fernando Verdasco won their quarter-final clash 6-4, 6-4.
Stan Wawrinka motors along after comeback, but worrying signs about his long-term future hard to ignore
The Wawrinka we have come to admire (and fear) has never been a small-tournament or small-opponent guy. But is that just our spoiled selves talking? Would it really be such a bad thing if Wawrinka never reached another Slam final?
Saint Petersburg Open: Stan Wawrinka downs defending champion Damir Dzumhur; top seed Dominic Thiem enters semi-finals
Stan Wawrinka beat last year's St Petersburg champion Damir Dzumhur in straight sets to reach the semi-finals on Friday.