Serena Williams struggled during changeovers. (Miguel Medina / AFP / Getty Images)

In one of the more dramatic if not overpowering performances of her career, Serena Williams overcame illness to overwhelm Timea Bacsinszky and advance to the French Open final.

Williams, battling a bad case of the flu, won 4-6, 6-3, 6-0 and will play 13th-seeded Lucie Safarova in the final at Roland Garros on Saturday.

“I don’t think I’ve ever been this sick,” a weary Williams told ESPN afterward. “I can’t believe I won. I got the flu after my third-round match. I’ve been struggling ever since and haven’t gotten better.”

Williams, 33, had bags under eyes and a coughing fit interrupted her interview with French TV. Given how ill she appeared, it was amazing that she was upright. On changeovers, she wept and, down 2-3 in the second set, she appeared to throw up into a towel. After that, she won 10 games in a row, somehow, on the warmest day of the tournament.

“I honestly don’t know [how],” she said. “I thought I was going to lose and I thought if I’m going to lose, I’m going to go for winners.”

Serena Williams powered through to the French final. (Miguel Medina / AFP / Getty Images)