NEW YORK -- Venus Williams arrived at this U.S. Open with a bum knee. She hadn't played a match in more than two months. She hadn't reached the semifinals at any Grand Slam tournament in more than a year.
And now? Williams is two victories away from her first U.S. Open title since 2001.
The No. 3-seeded Williams overcame nine double-faults and a total of 33 unforced errors to beat reigning French Open champion Francesca Schiavone 7-6 (5), 6-4 in the quarterfinals Tuesday night.
"I want to be in the final, because then obviously it's just one more step," the 30-year-old Williams said. "But I'm just focused on the semis, and I don't get too excited unless the tournament is over."
Next up for Williams is a semifinal against defending champion Kim Clijsters, who ran her U.S. Open winning streak to 19 matches by eliminating French Open runner-up Samantha Stosur 6-4, 5-7, 6-3. Clijsters and Williams have split their 12 previous meetings, but the Belgian won the most recent four, including in the fourth round in New York in 2009.
"Venus is a great competitor. She's been playing some really great tennis these last few matches," Clijsters said. "I look forward to it. It's a challenge."
Williams is the only American singles player left in the tournament, because the last of the country's 15 men in the field, 20th-seeded Sam Querrey, lost 7-6 (9), 6-7 (5), 7-5, 4-6, 6-4 to No. 25 Stanislas Wawrinka of Switzerland earlier Tuesday.
Asked whether she sensed any responsibility to carry American hopes, Williams smiled and replied: "If I felt like that, I don't think I'd be able to even raise my arms. Thankfully, I don't feel that way. I think my expectations are enough to deal with, so I'm just going to hopefully temper that."
Her own expectations are based, of course, on a lengthy list of successes, including seven Grand Slam singles titles. Two came at the U.S. Open, in 2000 and 2001. But she last made the semifinals at Flushing Meadows in 2007, and she hasn't played in the title match since losing to her sister Serena in 2002.
"I feel really comfortable here," Williams said, "and it's great to come back to a place where I have won, and a place where I've played well."
Querrey-Wawrinka lasted nearly 4˝ hours, meaning Williams-Schiavone didn't start on the same Arthur Ashe Stadium court until after 6 p.m.
But Williams didn't mind the delay one bit.
"I'm a pro at waiting for my match: Singles, doubles, you name it, I've waited. I've waited for rain delays. That's a part of tennis," said Williams, whose other five major singles championships came at Wimbledon. "I'm a pretty laid-back person, so I don't get too tight waiting."
She and the sixth-seeded Schiavone both found it tough to play the way they wanted, thanks to swirling wind that Williams said made it impossible to practice serves during the warm-up time, because her ball tosses kept going astray.
Still, she handled the conditions better in the end, improving to 8-0 against Schiavone.
The key was the tiebreak, when Williams went ahead 4-0 with a backhand passing winner on the run. She moved well all evening, showing not a shred of a sign that there is anything wrong with her left knee. Williams sprained that kneecap in early August, which kept her from playing any hard-court tuneup events before heading to New York.
Schiavone, though, took the next four points to even things. Then she made it 5-all by winning a 12-stroke exchange with a volley, celebrating by skipping and pumping her fist -- the sort of excellence at the net and general exuberance she showed en route to the title in Paris, where she became Italy's first female Grand Slam champion.
But then came two shots Schiavone would come to regret. First she pushed a backhand long to give Williams a set point at 6-5. Then she sailed a forehand long to end the set.
"I'm so angry," Schiavone said afterward. "Instead of attacking and going for the lines, I should have played a little safer and put the ball in."
Here is why that set was so crucial: Williams entered Tuesday with a 51-1 record at the U.S. Open when winning the first set -- the only loss was 4-6, 7-5, 6-1 to eventual champion Clijsters in the 2005 quarterfinals.
So while Schiavone could insist, as she did, that "When you lose the first set, you still have every chance to win the match," Williams is now 52-1 in New York when the opening set is hers.
"I feel like when the stakes were higher," Williams said, "I was able to raise my game."
Now comes the time to do that in the U.S. Open semifinals. And, if Williams gets her way, in the final, too.
Clijsters and Stosur both found the swirling air a problem, particularly when serving. There were a total of 15 service breaks, including a stretch in which there were nine in a span of 10 games.
"I don't think either of us played our best tennis tonight, by any means," said Stosur, whose fourth-round match ended at 1:35 a.m. Monday, the latest finish for a women's match at the U.S. Open.
She got broken all four times she served in the final set.
Clijsters managed to hold in each of her last two service games, finishing things off with an ace, her fifth of the evening.
"Yeah, that's probably all the frustration that comes out at the end," Clijsters said with a smile. "I'm just going to try and just remember the last serve I hit today and just try and focus on that one."
The Belgian won the U.S. Open the last two times she entered, in 2005 and -- after taking off 2˝ years to get married and have a baby -- in 2009. Now she is trying to become the first woman since Williams in 2000-01 to win the tournament two years in a row.
Clijsters has won 25 of her last 26 matches in the tournament, but Stosur felt she had her opportunities to get to the U.S. Open semifinals for the first time.
"I know Kim's a great player and a very tough opponent here. I mean, it wasn't the easiest match to win," Stosur said. "But when you have chances like that, that's what's disappointing -- not to kind of lose 'em on your own racket. I don't think she really stepped up and hit 12 winners to break my serve three times in a row."
Clijsters double-faulted eight times, made 43 total unforced errors and lost seven of her 19 service games.
"After the match, I was like, 'How did I win this?' I didn't feel like I was playing well; Sam is a good player," Clijsters said, "so I was just kind of talking to my coach and fitness coach and just [saying], 'Wow. What just happened? How did I win?"
Continued Clijsters, who had 16 unforced errors on forehands, 17 on backhands: "Next match, everything will have to be a lot better."
Information from The Associated Press was used in this report.