U.S. Open: Wozniacki d. Peng

NEW YORK—A semifinal pulsating with extended, physical rallies escalated into a punishing test of survival beneath the sweltering sun. Struggling to stay upright, Peng Shuai leaned on the blue back wall for support, while a concerned Caroline Wozniacki stared at her afflicted opponent—as well as a break-point deficit.

Peng would take a 10-plus minute medical assessment timeout, then return to court covering her mouth with her hand on the verge of tears. When Peng, who played a few more points, crumpled to the court in debilitating pain minutes later, chair umpire Louise Engzell mercifully called a halt to a frightening and bizarre match that should not have been permitted to continue.

The 10th-seeded Wozniacki held a 7-6 (1), 4-3 lead when Peng was officially counted out and carted off the court in a wheelchair. It appeared Peng was suffering from cramps; tournament director David Brewer told CBS' Mary Joe Fernandez it was "heat illness." It wasn't the way Wozniacki wanted to advance to her second career Grand Slam final, but the excruciating end propelled the former No. 1 back into Flushing Meadows title bout, which she also contested in 2009.

The 39th-ranked Peng had not lost a set en route to her first career Grand Slam semifinal in her 37th major appearance and broke for 6-5 to serve for a one-set lead. The good news for Peng was she wasn't staring into the sun; the bad news was the swirling wind was at her back. Wozniacki worked the middle of the court with plenty of margin, breaking back at 15.

Digging in, Wozniacki hit with depth, ran with determination, and sent Peng the message she'd have to hit a couple of lines each rally to win points. Three mini-breaks opened the tiebreaker, then Wozniacki relied on her legs and changed up her spins to draw three straight errors for 5-1.

Peng sailed a backhand to hand Wozniacki a fistful of set points. She needed only one, banging a body serve to cap the 76-minute opener on a seven-point run. A couple of times Peng winced in apparent pain after long rallies and once leaned on her Head racquet like a cane for support.

Undeterred, Peng broke for a 2-0 second-set lead. The Roland Garros doubles champion came forward the next game, and Wozniacki drilled a backhand right into her body. Peng blocked a reflex volley off the tape but Wozniacki lifted a slick lob, eventually breaking back for 1-2. Clutching an ice towel closely around her neck like a kid holding a blanket tightly to ward off a chill, Wozniacki, who later revealed she was bedridden with illness in recent days, took medication for a viral illness.

After saving a break point during a hold for 2-all, Wozniacki reached 0-40 after Peng's third double fault of the day. Wozniacki belted a backhand return down the line to snatch her seventh straight point and secure the break for 3-2.

Applying an ice towel to her legs on the next changeover, Peng gamely tried to hang on, holding after deuce for 3-4, but her body rebelled. Grabbing at her legs as if trying to pinch back advancing pain, Peng dropped her racquet and retreated to the back wall after a Wozniacki double fault. Supported by the trainer and the wall, Peng took some medication and a sports drink and was helped off the court. At that point, it seemed someone needed to step up and stop it. No one did, and Peng was allowed to continue playing. She even earned another break point with a return winner.

The Chinese star was permitted a 10-minute medical timeout—with no point penalty or warning—and was allowed to return to play, which seemed unfair to Wozniacki and downright hazardous to Peng, who shanked a return, fell to her knees, and rolled on her side in a near-fetal position while the trainer wrapped a towel around her. Wozniacki crossed the net to check on her fallen opponent before an EMS worker and trainer helped the 28-year-old to a wheelchair. A semifinal that began with so much promise finally came to a disturbing conclusion.

"Definitely very difficult; you're out here and you want to battle and finish it off properly," Wozniacki told Mary Joe Fernandez afterward. "I feel very sorry for Peng because she played really well out there and it was really hot on court."