Serena fights back to down Barty in second round

The American, who has triumphed three times at Roland Garros, is making her return after the birth of her daughter.

"I lost the first set and I thought I've just got to try harder and Serena came out," said a beaming Williams after giving her skin-tight, black catsuit another outing. "Every day is a great day I'm excited to... fight my heart out."

She won her opening match against Krystina Pliskova, but struggled from the outset against Barty in the evening encounter on Philippe Chatrier.

Barty took the first set 6-3 with typically combative, speedy play and Williams had it all to do to turn the match around.

And when the 22-year-old broke Serena’s serve in the first game of the next set, it looked like she might be about to secure the biggest win of her career.

However, the 36-year-old rallied, breaking twice in the second set and then once in the third to win in one hour and 48 minutes.

"In the first set she gave me a hell of a lot of cheapies, a lot of errors," said theAustralian who had secured her highest ever seeding at a major in Paris.

"She's not quite at the level she was when she was at her best but that's expected. But her level when she's not quite on her best (form) is still bloody good.

"When push came to shove, the real Serena came out. And one of her best assets is that when her back is against the wall, the best comes out."