It was 90 degrees (32 Celsius) with 42 percent humidity when the 10th-seeded Azarenka took to the court Wednesday morning for a second straight steamy day of play at Flushing Meadows.

Azarenka was trailing 5-1 in the first set and not moving well when she fell to the ground, not appearing to twist or strain anything.

Medical personnel rushed out and yelled to the sideline to bring water. After a few minutes on the ground, Azarenka was helped into the wheelchair and moved off the court, with a trainer placing his hand on her neck to check her pulse.

There was no immediate update on her condition. About an hour after the match was called, her agent said Azarenka was being transported to the hospital. Dulko said Azarenka was conscious and responding when she walked over to make sure everything was OK.

Wearing an all-black tennis dress, Azarenka had been moving slowly throughout the match and didn't appear to twist or sprain anything when she fell to the ground.

Medical personnel rushed out and yelled to the sideline to bring water. After a few minutes on the ground, being sheltered by an umbrella, Azarenka was helped into the wheelchair and moved off the court, with a trainer placing his hand on her neck to check her pulse.

“I was scared,” said Dulko, who advanced to the third round. “She went to the floor. I was worried for her. I went to see her, brought some ice, did whatever I could do to help.” Dulko said the conditions were, indeed, brutal, though as of 1630 GMT, tournament officials had not put in place their extreme weather policy, the way they did on Tuesday, when temperatures reached into the mid-90s. It was expected to be as hot Wednesday.

“It's tough to play out there,” Dulko said. “It's really hot, really humid. You sweat so much, sometimes it's impossible to hold the racquet.”