Rafael Nadal and Roger Federer will meet in the last four of the Madrid Masters following victories on Friday.
Top seed Nadal raced to a comfortable 6-2 6-2 win over Michael Llodra while Federer saw off Robin Soderling 7-6 [7-2] 6-4 in the later quarter-final.
"I didn't think I would win like that," said Nadal after his 36th consecutive victory on clay.
"He's got a strong serve and dangerous volley so it's hard to pass him. But in the first set he committed errors."
Nadal, who had a walkover in the previous round after opponent Juan Martin del Potro was forced to pull out injured, added: "Winning that first set gave me a lot of confidence."
The Spaniard looked relaxed and totally in control as he won the first four games of the match to gain the upper hand.
Llodra rallied briefly in the second but was always second best.
Nadal and Federer have met in the last two finals in the Spanish capital with the Swiss winning in 2009 and Nadal gaining revenge last year.
Former world number one Federer secured his only break against Soderling with a volleyed winner in the ninth game of the second set before serving out for victory in breezy conditions
He said: "The conditions were tough. I didn't know you could get so much wind inside an enclosed space."
Looking forward to Saturday's semi-final, Federer who has won only eight of 23 matches against Nadal, added: "He seems like he is playing amazing tennis right now but I'll give it my best shot and see how I get on."
The other semi-final will be contested between second seed Novak Djokovic and Andy Murray's quarter-final conqueror Thomaz Bellucci.
Djokovic overcame clay specialist David Ferrer 6-4 4-6 6-3, and in doing so extended his winning run in 2011 to 30 matches.
The Serb has now beaten the mark of 29 wins set by Czech player Ivan Lendl in 1986.
Only Bjorn Borg [33 in 1980] and John McEnroe [42 in 1984] have had longer winning runs from the start of a season.
Earlier, Bellucci became the first player through to Saturday's semi-finals with a 7-6 [7-2] 6-3 win over seventh seed Tomas Berdych.
The Brazilian, ranked 36th in the world, was in his element as he dominated on serve and did not have to face a single break point.
"The conditions on these courts are perfect for me, I like playing here," said Bellucci.