Second seed Aryna Sabalenka staged a fight-back to prevent Great Britain's Katie Boulter from pulling off a major Wimbledon upset on Centre Court.

Boulter, 24, looked on the verge of her biggest career win to date but Sabalenka came back to disappoint a raucous Centre Court crowd with a 4-6 6-3 6-3 second-round victory.

Not that the deciding set was a stroll for Sabalenka, although Boulter will rue a Hawkeye decision as she was about to walk back to her seat.

Sabalenka's ball, called out, had in fact shaved the line by the width of a blade of grass.

Sabalenka duly broke - but in an epic seventh game Boulter forced six break points with some impressive shot-making, including an exquisite drop-shot and lob combination.

However, the 23-year-old from Minsk repelled the lot and Boulter's chance had finally gone.

"It was a tough match, she's an unbelievable player," said Sabalenka. "It was a great atmosphere from the beginning to the end.

"Of course I was nervous today and didn't feel the court from the beginning but I'm glad I got my rhythm in the second set.

"I have one question guys, will you support me like this in the next round?"

World number five Elina Svitolina was made to work hard in a tight first-round match on Wednesday as the Ukrainian sealed a 6-3 2-6 6-3 victory over unseeded Belgian Alison van Uytvanck.

The pair traded breaks at the start of their second career meeting before Svitolina gained the upper hand following a tight game to go 4-2 up and the third seed held off a late fightback to claim the first set.

The aggressive Van Uytvanck mixed up her shots, with rifled drives and delicate drops, and took every chance to approach the net to break Svitolina for a 3-1 lead in the second set before levelling the match at one set apiece.

Both players wobbled on serve before 2019 semi-finalist Svitolina rediscovered her rhythm in the decider on Court One to close out the victory with a forehand winner.

It was an awkward afternoon for Elina Svitolina

"The return was quite good for me today. I was striking the ball really good. On important moments, I was calm and my shots were quite good in the end," Svitolina, who converted six out of 11 break point opportunities, told reporters.

There was little to separate the two with Svitolina sending down 34 winners - one more than Van Uytvanck - and both making 27 unforced errors.

"I'm just happy the way I was tracking the ball and that I could hold my nerve. This was very important for me today," Svitolina added.

In the second round, the 26-year-old takes on Poland's Magda Linette who beat unseeded American teenager Amanda Anisimova 2-6 6-3 6-1.

Alize Cornet plays a forehand at the net against Bianca Andreescu

Fourth seed Sofia Kenin's horrible 2021 continued as she crashed out of the second round.

The American, who won the Australian Open in 2020, was beaten 6-2 6-4 by compatriot Madison Brengle to become the biggest casualty in the women's draw so far.

Kenin only made it to the second round at this year's Australian Open and got to the fourth round in the French Open.

She has complained about feeling pressure since her maiden grand slam title last year and would have expected to beat Brengle, who is ranked 82 in the world.

An incredible first set saw just two hold of serves and Brengle got them both as Kenin was broken on all four of her service games.

The second set was much more even, until the latter part where Brengle got the vital break to equal her best ever run at Wimbledon.

Fifth seed Bianca Andreescu is also out after losing in the first round to Alize Cornet.

The former US Open champion was playing just her second ever match at SW19 and first since 2017, but was taken down 6-2 6-1.

Cornet is a handy player on grass and dropped just three games as she wrapped up the win in 81 minutes on Court Two.

The match was cancelled on Tuesday because of rain and Andreescu will wish it never started on Wednesday.

The 21-year-old is making her way back from a serious knee injury which curtailed her career after her surprise US Open win in 2019 and will now be able to concentrate on the American hard-court swing after taking a beating.

A run of eight successive games for Cornet at the end of the first set and into the second decided this one, with the Frenchwoman going on to enjoy an easy win.

Five-time champion Venus Williams is out after losing 7-5 6-0 to Ons Jabeur.

The 41-year-old, who first won at SW19 in 2000, was run ragged by the Tunisian, who recently won a pre-Wimbledon warm-up in Birmingham.