Serena Williams' status for U.S. Open up in the air due to leg injury

Serena Williams still is waiting for the results of scans on her leg injury that forced her to withdraw from Wimbledon during her first-round match on Tuesday.

The 39-year-old flew home to the United States Wednesday and was walking, which her coach Patrick Mouratoglou said is a "good sign."

"We don't know for the moment; we are expecting the result of the clinical assessment," Mouratoglou told TennisMajors.com. "The manual test gave us an idea of the nature of the injury, not how serious it is. We're waiting to see how long she's supposed to be resting and, obviously, the consequences in terms of preparation for the next one [the US Open]. Time will fly. She's walking, which is a good sign, and it excludes very bad possibilities."

Williams withdrew at 3-3 in the first set of her match against Belarus' Aliaksandra Sasnovich. She slipped on Centre Court while leading 3-1 and was unable to recover. The Michigan native left the court in tears after the withdrawal, and Mouratoglou suggested it was because she does not know if she'll ever compete at Wimbledon again.

"She'll be 40 soon; she doesn't know how many Wimbledons she will play in the future," he said. "Probably not that many, you can't be sure there will be another one. So many feelings going on in her head in a small amount of time."

Mouratoglou added that Williams' injury was even more disappointing because they both believed she was in the right shape, physically and mentally, to win Wimbledon. If she had won, she would have equaled the Grand Slam record of 24 held by Margaret Court. 

Williams was one of several players affected by the slippery courts at this year's Wimbledon. Mouratoglou suggested the tournament look at its policy regarding grass-court shoes in order to prevent injuries in the future. 

The US Open is slated to begin late next month. Williams has won the US Open six times, with her latest victory coming in 2014 as she defeated Caroline Wozniacki in the Final, 6–3, 6–3.