MASON, Ohio (AP) -- Roger Federer didn't let one frustrating game ruin everything.
The top-ranked player overcame a momentum-changing second set Friday, recovering to beat Nicolas Almagro 6-3, 3-6, 6-2 in the quarterfinals of the Western & Southern Financial Group Masters.
Federer will face Lleyton Hewitt in the semifinals, looking to extend his 10-match winning streak against the Australian. Hewitt coasted to a 6-2, 6-4 win over a heat-sapped Carlos Moya.
Ninth-seeded James Blake also advanced the semifinals by beating Sam Querrey 5-7, 6-4, 6-4 later Friday night in a matchup of Americans.
For a few minutes in the early afternoon, it appeared that a tournament full of upsets might have the most stunning one yet.
The 21-year-old Almagro had the crowd behind him during the second set, when he matched Federer shot for shot, moved him around the court and won the only break point of the set.
"I had one really bad game and it cost me the set," Federer said. "It happens. I'm happy that it doesn't happen every match."
It was only the second set Almagro had won off Federer. The Swiss star, however, stopped his momentum right there, breaking Almagro's serve to go up 2-0 in the third set. After Federer held serve to go up 4-1, Almagro tossed his racket away in frustration, then had his left calf massaged during the break.
Nothing in Almagro's past suggested he could give Federer such a tough time. He hasn't played well on hard courts -- he's 6-17 on the surface -- and had beaten him one set in their previous four matches.
This time, he took him to the limit.
In the earlier quarterfinal, Hewitt looked much fresher than Moya at the end of an oppressively hot week. Temperatures on the court reached 110 degrees Thursday, when the 30-year-old Moya sweated out a three-set victory to reach the quarterfinals.
"I'm not 20 years old anymore, so I felt it a little bit," Moya said.
The 26-year-old Australian had a lot more energy in his game, which has been sharp lately.
"On any given day, I feel I'm capable of beating anybody in the game," said Hewitt, currently ranked No. 19. "The last few months, my body has felt very good. That makes it easier to go out with confidence and play the way I want to play."
Moya served to open the match, fell behind 0-40 and was broken, setting the tone. Hewitt had only two unforced errors during the opening set.
He broke Moya again to open the second set, leaving the Spaniard shuffling around the court with his head down. Trailing 3-0, he took an injury timeout to have a bothersome blister on his right foot treated. The crowd then got behind Moya, who rallied briefly before Hewitt finished him off.
Hewitt's next challenge is trying to beat Federer, something he hasn't done in four years. Federer has won their last 10 matches, including a 6-3, 6-4 victory in the quarterfinals in Montreal last week.
"I didn't think of it as nine in a row before last week because we hadn't played in two years," Federer said. "In two years, a lot happens. From my point of view, it's 1-0."
Blake and Querrey played a close-as-could-be match last month in Indianapolis. Querrey served a career-high 34 aces -- including 10 in a row -- while winning in three sets, all of them decided by tiebreakers.
They went the distance again in a much sloppier match.
The 19-year-old Querrey had trouble with his serve, but was steadier in the first set. Blake got his first break of the match to pull ahead 3-2 in the second set.
Querrey momentarily lost his composure after he fell behind -- one backhand return skimmed the edge of his racket and plopped into the seats behind him.
Blake, who had to pull out of Montreal last week because of strained abdominal muscles, was more aggressive in the final set, coming to the net to gain the upper hand. He crouched and pumped his fists after breaking Querrey's serve to go up 4-3, then served it out and finished it off with an overhead slam at the net.
It's the second time the 27-year-old Blake has reached a Masters semifinal -- he lost the title match at Indians Wells to Federer last year.