Victoria Azarenka moved into the Wimbledon second round as the world number two played through the pain barrier to defeat Portugal's Maria Joao Koehler 6-1, 6-2 on Monday.
Azarenka, the reigning Australian Open champion, recovered from a nasty fall in the second set that left her in tears to earn a meeting with Italy's Flavia Pennetta.
The Belarusian had looked set for a routine victory until the right knee injury threatened to derail her latest attempt to reach a first Wimbledon final.
"It was such a shock to me, I slipped and felt my body collapse," Azarenka said.
"It was very emotional. I was in shock. I was in such pain at the beginning, it wouldn't let go.
"But then it calmed down. I was trying to stay in the moment and give my best.
"I almost slipped one time before that and I saw my opponent slipped as well. We are not on clay anymore so I have to be more careful.
"I'm going to do the best I can to be ready for the next match."
Azarenka was leading 6-1, 1-0 on Court One when she slipped while trying to move into position after serving.
She collapsed in agony and immediately began to cry before shouting out 'oh my god'.
With popstar boyfriend Redfoo looking on anxiously from the players' box, Azarenka was comforted by the umpire and the tournament supervisor before a doctor arrived to examine the injury during a medical time-out.
After a delay of around 10 minutes, the 23-year-old continued playing but with her right knee heavily strapped.
Azarenka was moving tentatively and it was no surprise that she served three double faults to hand a break back to Koehler.
But she showed impressive courage to keep going and broke again before receiving more treatment at the change-over.
Koehler also slipped at the same end of the court in a similar fashion but she avoided doing any serious damage.
Azarenka has suffered semi-final heartache at Wimbledon for the last two years, losing on both occasions to the eventual champion, Petra Kvitova in 2011 and Serena Williams 12 months ago.
She also lost to Williams in the last four at last year's London Olympics at Wimbledon.
In the circumstances it would have been a devastating blow for Azarenka to have to withdraw.
But, finally looking more comfortable in her movement, she was able to finish off the world number 106 without further alarms.