Serena Williams admitted she was close to panicking after rolling her ankle in her crushing Australian Open first round victory.
The third seed and former winner stumbled and fell during the first set against Edina Gallovits-Hall but recovered to thrash the Romanian 6-0, 6-0.
She admitted she was uncertain of the state of the injury, which was almost identical to the one that forced her withdrawal from last year's Brisbane International.
"I think I was really, really close to panicking because a very similar thing happened to me last year, almost on the same side, the same shot," Williams said.
"So I almost panicked, and I thought, I can't do that. I just have to really remain calm and think things through."
Despite taking an injury timeout while ahead 4-0 in the first set, Williams returned to complete the emphatic win, but her movement was kept to a minimum.
She may have scans to see if there is any structural damage but is hoping for the best.
"That's definitely optional. I'm going to play it by ear," she said. "I would love to see the next few hours how I go, and then I'm going to decide what to do next at that stage.
"Obviously there's pain, obviously there's swelling. So it's going to be really important to see how the next few hours unfold."
Defending champion Victoria Azarenka beat Romanian Monica Niculescu 6-1, 6-4 after a shaky second set.
"I started well but I struggled a little in the second set," Azarenka said. "But I'm glad I'm still winning."
Earlier Danish star Caroline Wozniacki overcame a wildly erratic Sabine Lisicki to squeeze into the second round.