(CNN) -- Roger Federer is on course to claim a fourth Cincinnati Masters title after world No. 1 Rafael Nadal and No. 3 Novak Djokovic followed fourth seed Andy Murray in crashing out of the U.S. hardcourt tournament on Friday.
Defending champion Federer, beaten by Murray in the final in Toronto last weekend, will face Marcos Baghdatis in Saturday's semifinals after the Cypriot upset Nadal 6-4 4-6 6-4 on Friday night.
Third seed Federer, seeking only his second title this year following January's Australian Open success, beat Russian sixth seed Nikolay Davydenko 6-4 7-5.
He was facing a break of his serve at 4-4 in the opening set but then reeled off five straight games to take control, after a quiet week in which two of his matches were decided by opponents' injuries.
"I felt like I played really good considering I had not played well this week yet," the Swiss star told the ATP Tour website.
"Today I had a good 10 minutes, and all of a sudden I'm up 6-4, 2-0. You don't know what happened, but you're in the lead. So it's just the way it goes. You've got to make the best of it."
Baghdatis, once ranked eighth in the world but now 20th after a time outside the top-100, beat Nadal for the first time in his career following six defeats to the Spaniard.
The 25-year-old lost to Federer in the final of the 2006 Australian Open, but beat him for the first time in seven career meetings at Indian Wells in March.
"I was serving pretty big. Basically I took my chances. Other times I played him I had chances, and I didn't take them. I know that Rafa will not give me the match, so I had to go and take it," he said.
"Break-point at the end, he made a double fault because the whole match I was putting so much pressure. So he felt the pressure."
Two-time finalist Djokovic was dumped out by Andy Roddick, who will face close friend Mardy Fish in the first all-American semifinal in Cincinnati since 2004.
Roddick triumphed 6-4 7-5 against the second seed, beating the Serbian for the fifth time in seven meetings to ensure he will return to the top-10 when the world rankings are released next week.
"Novak probably didn't play his best today. That's fairly apparent," Roddick said. "He's missing balls he normally doesn't miss. So I probably expected him to play a little bit better."
Fish set up a repeat of the 2003 final, which Roddick won, by beating Murray 6-7 6-1 7-6 in the first quarterfinal -- a result which ended the possibility of the world's top four players reaching the semis for a second successive week.
Fish took advantage of Britain's Murray visibly wilting in the stifling heat to become the first unseeded player to reach the last four since Lleyton Hewitt in 2007.