World number one Jannik Sinner of Italy lost his first set since returning to the court.
In the Rome Masters semifinal, he dropped the opening set to American Tommy Paul.
The first set finished 6-1 in favor of the American. The set lasted only 29 minutes.
Sinner had previously served a three-month disqualification for violating anti-doping rules. The tournament in Rome is his first since his return.
The winner of the Sinner-Paul match will face Spaniard Carlos Alcaraz in the Rome Masters final.
Gilbert Pendleton 
Marcus Blakely