LONDON: Defending champion Serena Williams narrowly survived a major scare at Wimbledon on Friday, coming from behind to overcome gritty US compatriot Christina McHale in a thrilling second round encounter on Friday.

The world number one defeated McHale 6-7 (7/9), 6-2, 6-4 in two hours and 29 minutes on Center Court, only just avoiding what would have been her earliest-ever Wimbledon defeat.

The six-time Wimbledon champion will face Germany’s Annika Beck for a place in the last 16.

“It was a really good match. She played great and she always plays great against me,” Williams said.

“I know mentally no-one can break me. I knew, down a break in the third, that I was going to have to put my mind in it and that’s what I did.”

Several times throughout the match, Williams was left cursing the bounce of the ball or screaming at the heavens as she struggled to find her form against the world No. 65.

McHale was set point down in the 10th game of the first set but challenged when Williams thought she had won the point — and Hawk-Eye technology showed the tiniest sliver of the ball was in, giving the outsider a reprieve.

McHale recovered and fashioned a few set points for herself before sealing it on the tie break.

Earlier sister and five-time champion Venus Williams reached the Wimbledon last-16 on Friday, seeing off Russian teenager Daria Kasatkina 7-5, 4-6, 10-8 in a tie featuring a rain stoppage when she held match point.

Williams, 36, was 7-6, 40-30 up on Kasatkina’s serve in the final set on Court One when the tie was halted by the second rain delay of the day.

Seventy-five minutes later, the players returned with Wimbledon debutante Kasatkina saving the match point, the second of the day.

But Williams eventually triumphed at the third time of asking when the 19-year-old dumped a forehand into the net.

Williams, the eighth seed, goes on to face Spain’s Carla Suarez Navarro for a place in the quarterfinals.

Juan Martin del Potro admitted he felt “alive again” after the injury-plagued former US Open champion sent Swiss fourth seed Stan Wawrinka crashing out of a wet and wild Wimbledon on Friday.

On a day when rain caused a 10th delay of the week, forcing organizers to consider playing on the middle Sunday for the first time since 2004, the giant Del Potro shone beneath the Center Court roof.

Playing in his first Grand Slam tournament since the 2014 Australian Open, his 3-6, 6-3, 7-6 (7/2), 6-3 second round victory over Wawrinka brought back memories of his stunning 2009 US Open win before a series of wrist injuries pushed him to the brink of retirement.

The world No. 165 from Argentina, who was a semifinalist in 2013 in what was his last appearance at Wimbledon, next faces French 32nd seed Lucas Pouille.

“It feels amazing, it’s a great sensation,” said the 27-year-old who has undergone three wrist surgeries in the last two years.

“I enjoyed the crowd. It’s an incredible feeling, that’s why my hands are still shaking.

“I feel alive again. After sitting at home for two years, this feels like a second or third career,” added the former world number four.

Wawrinka, a quarterfinalist in 2014 and 2015, fired 47 winners past Del Potro but was undone by 48 unforced errors.

“We are happy that he’s back. He’s a great guy off the court. He’s amazing player on the court. He’s big champion,” said Wawrinka.

Nick Kyrgios survived a warning for bad language and a third set sulk to clinch a 6-7 (3/7), 6-1, 2-6, 6-4, 6-4 victory over Dustin Brown in an explosive second round clash on Friday.

Kyrgios, seeded 15th, has earned a reputation as one of the most volatile players on the men’s tour after a series of distasteful antics, including briefly appearing to stop trying during his Wimbledon defeat against Richard Gasquet last year.

The temperamental Australian has been equally petulant on his return to the All England Club.

Kyrgios was warned for bad language following a foul-mouthed rant during his first round win over Radek Stepanek and he was at it again as he fought back to defeat German wildcard Brown.

The 21-year-old, who famously shocked Rafael Nadal en route to the Wimbledon quarter-finals two years ago, spent most of the match ranting, drawing a code violation for an audible obscenity and appearing to give minimal effort in protest as he sulked his way through the third set.

Despite his stroppy antics, Kyrgios advanced to play Spanish 22nd seed Feliciano Lopez or Italy’s Fabio Fognini for a place in the last 16.

“This match was always going to go five sets. He’s one of the toughest players to face on this surface. I’m really pleased to go through,” Kyrgios said after a match which was twice interrupted by rain.

“I knew I had to steady the ship. I went off course a lot in the third, but I thought he barely missed a shot.

“I got back on track in the fourth and fifth. It was a fun match.”

Kyrgios had predicted the Court Two clash between two of the tournament’s most flamboyant players would be a “circus” and the Australian was on the money.

Only eight matches had been completed with Czech 10th seed Tomas Berdych beating Benjamin Becker 6-4, 6-1, 6-2 and French 12th seed Jo-Wilfried Tsonga getting past Juan Monaco 6-1, 6-4, 6-3, also in the second round.