Paul came through a humdrum quarter-final encounter to reach the Foro Italico semis, where he awaits one of Sinner or Casper Ruud, for the second straight year.
I just feel comfortable out here and yeah I've been playing some good tennis this week," said the American
The world number one is yet to drop a set on home clay, but Ruud is on a hot streak and eyeing a second straight 1000 Masters triumph after breaking his duck in Madrid earlier this month.
Norwegian Ruud has won more matches on clay than any other player on the men's tour in the last five years, and Sinner is still finding his feet after his suspension, accepted from the World Anti-Doping Agency for testing positive for traces of clostebol in March last year.
If Sinner gets through to the semis, it will be the first time two Italians have reached the last four of a Master 1000 tournament since the series' creation 35 years ago, with Lorenzo Musetti facing Carlos Alcaraz on Friday.