It was an incredible moment at the U.S. Open: a top-ranked player keeled over in the brutal heat.
Azarenka's opponent joined officials and ball boys swarming around the stricken player, shielding her from the baking sun as they tried to revive her.
It turns out it wasn't just the heat. Azarenka had suffered a head concussion earlier in the day when she fell during a warm-up session.
As the game progressed and the temperature soared, she felt dizzy, then collapsed.
Azarenka was taken from the stadium to the hospital in a wheelchair. She was later released and is now recovering at her hotel.