Rafael Nadal is highly unlikely to defend his US Open title when the rescheduled grand slam tournament begins on 31 August, after confirming on Tuesday that he will play in the Madrid Masters, which starts on 13 September, the day after the final in New York. “I talked to my friend @RafaelNadal and he has confirmed his participation in Madrid next September!” the world No 56 and Madrid director, Feliciano López, tweeted. “We wait for you as always with open arms in the Magic Box!” Nadal replied to his Spanish compatriot: “See you in Madrid in September. Meanwhile everything goes well!” The Madrid and Rome Masters, which starts on 20 September, are the key warm-up clay tournaments before the French Open, rearranged to begin on 27 September. They are also the fiefdoms of the 34-year-old Nadal, who has won 12 titles at Roland Garros, as well as five in Madrid and nine in Rome. He defeated Daniil Medvedev in the final last year to win his fourth US Open title. However, uncertainty about quarantining for players returning to Europe remains a significant disincentive to travel to New York for many on the ATP Tour, which has been suspended since March. Nadal and the world No 1, Novak Djokovic, are among many contenders for the US title who have expressed reservations about playing in New York during the coronavirus pandemic, doubts that were strengthened when the city’s marathon was cancelled last month. Andy Murray has said he is keen to play at Flushing Meadows, where he won the first of his three major tiitles in 2012, and had intended to also play in the Citi Open in Washington on 14 August. The EU has been giving regular updates on quarantining requirements and several European players are waiting for clarification before committing to travelling to Washington, the first warm-up event for the US Open, which has incorporated the Cincinnati Open in its expanded schedule. There is a feeling among many whose realistic ambitions do not stretch to winning the US Open that they are better off playing in the two pre-Roland Garros events, in Madrid and Rome, rather than risking complications getting to and from Washington and New York. A reliable source at the ATP told the Guardian on Tuesday: “That is a big question at the moment. It’s still not a clear picture.”