Rafael "Rafa" Nadal said on Monday he had tested positive for Covid-19 after returning from his comeback appearance at the Mubadala World Tennis Championship exhibition event in Abu Dhabi last week.

The 20-times Grand Slam champion and former world number one said he was having some "unpleasant moments" but was hoping to feel better soon and would keep people informed about his plans over future tournaments.

The positive test casts further doubt on whether the 35-year-old participates...