Wimbledon 2019: Serena Williams survives scare and will next meet Jo Konta's conqueror Barbora Strycova

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Serena Williams admitted she had to fight all the way to overcome Alison Riske and move a step closer to an eighth Wimbledon title.

A thrilling 6-4 4-6 6-3 victory in the all-American showdown on Centre Court ensured the 37-year-old reached her 12th semi-final in 19 appearances at the Championships.

Riske, unseeded and ranked 55, had knocked out world number one Ashleigh Barty 24 hours earlier, and she pushed Williams all the way.

But for Riske there was no reward despite five breaks of serve - converting every single break point she created - against the 23-time grand-slam winner.

"I just needed to just fight," admitted Williams. "Alison, I mean, she played great throughout the whole tournament. She's beaten so many amazing players, players that have had great years. She was not giving it to me. I needed to step up and take it. That's what I had to do."

Having been pegged back to 1-1 by the stubborn Riske, Williams seemed to find a second wind after tying her hair up.

She added: "It was just in my way. I was missing a shot because it was in my face. I was like, 'this is not happening'. I just needed to get it out of the way, put the business bun up and just get to business."

Breaks were exchanged again twice at the start of the decider, the Americans matching each other blow for blow until a stunning Williams volley and a Riske double-fault broke the 29-year-old once more.

Serving for the match after two hours and one minute, Williams fired a 19th ace down the middle to seal her place in the last four. It was her toughest test yet, and proved that despite an injury-hit year, Williams has lost none of her physical strength.

Yet even she was perplexed by a decision to fine her almost £8,000 for damaging one of the Wimbledon courts with her racket during a practice session prior to the tournament.

"I just threw my racket. I got fined," she said. Asked how much damage she had actually done, Williams replied "I mean, I guess if you could tell me, I would appreciate it. I have always been an Avenger in my heart. Maybe I'm super strong, I don't know."

Williams will now face Barbora Strycova, who reached her first grand slam semi-final after shocking British hope Johanna Konta.

The 33-year-old from the Czech Republic came from 4-1 down in the first set to win 7-6 (5) 6-1 on Centre Court.

Strycova's only other quarter-final appearance at a major tournament was here five years ago, but on Thursday she will get a shot at seven-time winner Williams for a place in the final.

"It sounds crazy. It's happening but I can't really believe it," she told the BBC.

"It was one of the best matches I've played here. I haven't been playing on Centre Court so it was a special moment.

"It's a great week to play (Williams) and a match I look forward to."

The second semi-final sees seventh seed Simona Halep face Elina Svitolina, seeded eighth.

Romanian Halep found herself 3-0 down in the opening set as China's Shuai Zhang briefly threatened a shock.

But Halep recovered to take the first set on a tie-break and then raced through the second to win 7-6 (4) 6-1.

Halep said: "I expected her to play so well, she beat me the last two times that we played.

"I was a little bit nervous before the match, a little bit stressed. I knew that she's going to come and hit the balls very strong.

"Also when she hits them, the ball doesn't bounce that much. It's really tough to return.

"But I kept fighting. I knew that I have to be 100 per cent for every ball, then I will break her rhythm a little bit. It happened in the second set."

Ukrainian Svitolina was a 7-5 6-4 winner over Czech Karolina Muchova to advance to her first grand-slam semi.

Related Wimbledon 2019 links

• Click here for printable men's draw PDF
• Latest Wimbledon odds
• Wimbledon men: The contenders
• Wimbledon women: The contenders
• Wimbledon: By the numbers
• Wimbledon: Talking points