NEW YORK (AP) - Simona Halep appreciated the help from the heavens in her U.S. Open quarterfinal.
Worn down after dropping the second set to Victoria Azarenka, the second-seeded Romanian got to rest up for nearly an hour-and-a-half when the sky opened up.
''Thanks, God, for raining,'' she said in an on-court interview after her 6-3, 4-6, 6-4 victory Wednesday.
Halep, who's just 5-foot-6, came back on court with a 106 mph ace to prove just how fresh she felt. She advanced to face 26th-seeded Flavia Pennetta, who beat two-time Wimbledon champion Petra Kvitova in another three-set match earlier Wednesday.
Azarenka also is a two-time major champ - as well as a two-time U.S. Open runner-up. Her big-match experience showed for much of the afternoon against Halep, who was seeking to reach just her third major semifinal and first at Flushing Meadows.
The 23-year-old Romanian had 40 winners to 19 unforced errors, while Azarenka had 38 winners to 42 unforced errors. At key moments, though, Azarenka was better, converting all five of her break-point chances while Halep was 6 for 19.
But when that final break point came at 3-3 in the third set, Halep converted it, and that was enough to squeeze out the victory with Romanian gymnastics gold medalist Nadia Comaneci cheering her on.
''To have a great champion in your box, it gives you power, that she appreciates what I'm doing,'' Halep said.
The rain came in the fourth game of the final set and delayed the match for 1 hour, 25 minutes. Azarenka had broken Halep in her first service game of the set only to be immediately broken back.
''I was a little bit surprised by the pace of her ball, to be honest,'' Azarenka said.
Azarenka was seeded just 20th after two injury-plagued seasons and hadn't been to a Grand Slam semifinal since the 2013 U.S. Open. In that time, Halep has soared up the rankings, reaching last year's French Open final.
Both women's quarterfinals Tuesday also went to three sets, the first time since the 1982 U.S. Open that all four women's quarters went the distance at a major.
Pennetta rallied from down a set and a break to reach her second U.S. Open semifinal in three years.
''In the second set, I was really in trouble,'' Pennetta said. ''I just keep going, playing, playing. It's unbelievable.''
In 38 career appearances at the other three majors, Pennetta has reached the quarters just once. She's done it six times in seven years at Flushing Meadows, including her only two trips to a Grand Slam semifinal.
''Before the tournament I never think to be so far in the tournament, so it's something special,'' said Pennetta, who had lost five of her last seven matches coming into the U.S. Open.
The win by the 33-year-old Pennetta means that three of the women's semifinalists at a major will be at least 32 for the first time in the Open era. She joins another 33-year-old, Serena Williams, and fellow Italian Roberta Vinci, 32.
When a reporter started to apologize for asking Pennetta about her age, she playfully interrupted: ''We are old. I know.''
It's also the first time in the Open era, which started in 1968, that two Italian women have reached the semifinals in the same Grand Slam tournament.
Pennetta beat the fifth-seeded Kvitova 4-6, 6-4, 6-2 on a steamy afternoon. Kvitova, who has battled mononucleosis this summer that's limited her practice time, was struggling physically by the end of the 2-hour, 23-minute match.
''Just from the beginning of the match I didn't really feel 100 percent ready today,'' Kvitova said.
The U.S. Open has been the least successful major for the Czech lefty. Because of the illness, she wasn't expecting this would be the year she advanced past the fourth round for the first time.
''It wasn't really (an) easy situation,'' she said. ''I'm kind of proud of myself how I played here.''
She led 3-1 in the second set Wednesday but couldn't close out the match, committing 60 unforced errors.