Monfils lost to Austria's Dominic Thiem on Tuesday in three sets but appeared to suffer a problem during the second set.

The umpire asked after the Frenchman's health but he claimed he was fine and when Thiem posed a similar question at the net after the match's conclusion, Monfils shrugged off his concerns.

However, the 30-year-old pulled out of the ATP World Tour Finals on Wednesday with a rib muscle injury and was not able to face world No 2 Novak Djokovic at the O2 Arena.