Djokovic is yet to drop a set at this year's Rome Masters
Reigning champion Novak Djokovic will face Roger Federer in the semi-final of the Rome Masters after they won their quarter-final matches in straight sets.
Djokovic beat Argentina's Juan Martin Del Potro 6-3 6-4, breaking the fifth seed three times in the first set.
Second seed Federer faced a stiffer challenge before beating German qualifier Mischa Zverev 7-6 (7-3) 6-2.
And Spain's world number one Rafael Nadal also reached the last four with a 6-3 6-3 win over Fernando Verdasco.
The scoreline did not do justice to Verdasco as Nadal secured a 28th consecutive victory on clay - his last defeat on the surface was to Juan Carlos Ferrero in the first round of this tournament last year.
The number six seed hit 20 winners to Nadal's six, but tellingly, he also had double the unforced errors of his compatriot.
And while Nadal converted four of six break point chances, Verdasco only made one of his six count.
"I was a little bit lucky, he made important mistakes in some important points," said Nadal.
Chile's Fernando Gonzalez awaits in the last four after the number 12 seed came from one set down to beat Andy Murray's conqueror Juan Monaco 2-6 6-3 6-4.
Switzerland's Federer also rode his luck in beating Zverev.
He missed two set points in game 10 of the first set and then lost the first point of the tie-break on serve.
But he bounced back quickly and took a 4-2 lead with a mini-break of his own from a trademark backhand cross-court pass.
Verdasco put up a tough fight against Spanish compatriot Nadal
Federer wrapped up the first set with a forehand pass as Zverev continued with his gameplan of attacking the net.
And having broken the German's resistance, Federer romped away with the second set.
Federer's victory sets up an intriguing semi-final with Djokovic, but the 13-time Grand Slam winner said he would have to improve his game.
"We haven't played each other that much on clay but he seems to be playing well again," said the 27-year-old.
"He's come through convincingly against tough players so I hope I can play better against him than I did against Zverev."
Djokovic, 21, is yet to drop a set in three matches in Rome and produced a commanding display to win in just under 100 minutes.
"I tried to change the pace a lot because I know that Del Potro likes more or less the same pace and he moves really well for his height," he said.
Three breaks in the opening set and an ace on set point underlined Djokovic's supremacy.
Del Potro increased his first-serve accuracy in the second set, but he sent a backhand long at 15-40 in the fifth game to hand his opponent a decisive break.
The Argentine saved three match points before finally succumbing on the fourth, hitting a cramped forehand into the net.