Roger Federer cruised to a 6-3 6-3 quarter-final win over Tomas Berdych as the second seed kept alive his hopes of an elusive Italian Open title.
Rome and Monte Carlo are the only two Masters series titles that the 17-time Grand Slam champion has never won.
The Swiss, 33, will face either seven-time Rome champion Rafael Nadal or Stan Wawrinka, who meet later on Friday.
Seventh seed David Ferrer beat David Goffin 6-2 4-6 6-3 and plays the winner of Novak Djokovic and Kei Nishikori.
Defending champion Djokovic is top seed in Italy going into the French Open, which begins on Sunday, 24 May.