With Spain's Albert Costa and Carlos Moya and Argentina's David Nalbandian and Mariano Zabaleta all enjoying straight-set victories, the results merely underlined the current dominance of those two nations on Europe's slow clay courts.
Moya, French Open winner in 1998, was in imperious form.
Having edged out qualifier Ivo Karlovic in a tight last-16 match earlier in the day, the former world number one returned for his evening quarter-final in an altogether different mood, unleashing explosive groundstrokes to dispatch Romania's Andrei Pavel 6-1 6-2 in just 48 minutes.
"Maybe he felt a bit tired from yesterday's match (defeating Lleyton Hewitt), but I'm very satisfied with the way I played," said the sixth seed.
"It's going to be very tight and difficult for all of us in the semi-finals. The Argentines are tough opponents, they're fighters, but let's see if we can make it an all-Spanish final."
Moya next faces Zabaleta, who muscled Chilean Nicolas Massu off court 6-1 7-5, adding the eighth seed to a list of victims that includes defending champion Felix Mantilla and fourth seed Tim Henman.
IMPRESSIVE NALBANDIAN
Costa was first to reach the last four, cruising to a 6-2 6-3 victory over Jiri Novak of the Czech Republic.
The progress in Rome of the 2002 French Open winner, who accounted for world number one Roger Federer in the second round, was in sharp contrast to his last two outings in Monte Carlo and Barcelona, where he had failed to progress beyond the first round.
"Winning today was very important for my confidence," he said. "I'm coming out of a difficult period. I haven't been motivated. I didn't care much if I won or lost."
Costa's semi-final opponent is fifth-seeded Nalbandian, who posted an impressive 6-4 6-3 win over the last American left in the draw, Vincent Spadea.
The 22-year-old Argentine is among the most versatile players on the men's circuit and finished runner-up to Hewitt at Wimbledon two years ago.
He certainly made light work of Spadea, combining piercing groundstrokes and intelligent runs to the net to control the first set and then reel off six consecutive game to come back from 3-0 down in the second.
"They were difficult conditions out there today. The wind was making me serve not so good and I think that's when Spadea put in his best games. If I had gone down 4-0 it would have been difficult," he said.
Neither Costa nor Moya will relish the thought of meeting him. Nalbandian beat both on the way to claiming his first title two years ago in Palermo.
