The 2009 champion who will next face Roger Federer, saved two match points in the fourth set of what was arguably the best of the tournament so far.
Tennis fans expressed frustration that the players weren't getting better crowds.
'It's very emotional. I've been waiting for this moment since I was 14'
Britain's Johanna Konta will become the first British woman to reach the top 10 of the WTA rankings for 32 years on Monday after reaching the China Open final on Saturday.
Fritz delivers as US win inaugural United Cup crown
Serbian Dusan Lajovic beat Andy Murray at the Miami Open on Wednesday, sending the Briton packing in the first round with his first hardcourt win of the season.
Images from Day 5 of the 2023 Australian Open at Melbourne Park on Friday.
ATP says 'no evidence' against Harrison's racist remarks
Spain's Garbine Muguruza successfully defended her Monterrey Open title on Sunday when Victoria Azarenka retired injured from her first WTA singles final in three years.
Defending champion Simona Halep was knocked out of the French Open 6-2, 6-4 by 17-year-old American Amanda Anisimova in a quarter-final shock.
Images from the Australian Open in Melbourne on Thursday.
Simona Halep is prepared for her second marathon of the tournament when she faces former champion Angelique Kerber
Not many would have bet on unseeded Americans Danielle Collins and Frances Tiafoe making it to the Australian Open quarter-final
Images from Day 8 of the Australian Open in Melbourne on Monday.
Top seed Agnieszka Radwanska's title defence at the Sydney International lasted just 92 minutes when she was dumped out of the second round by Bethanie Mattek-Sands on Tuesday.
IMAGES from the US Open matches played on Day 1 at the Flushing Meadows in New York on Monday.
Images from Day 8 of the Australian Open at Melbourne Park on Monday.
Images from Day 7 of the 2022 French Open at Roland Garros in Paris on Saturday.
Stephens used her powerful game to the full in the first set, hitting winners almost at will, but Halep then stepped up a gear and went on to win 3-6, 6-4 6-1.
Novak Djokovic and Andy Murray will face off in a second claycourt final within eight days at the Italian Open after the two in-form players proved on Saturday that they will be the ones to beat at the season's second Grand Slam in Roland Garros.
Zverev, who is looking for his fourth tournament win of the year, needed only 64 minutes to defeat Nishikori and move into the final in WashingtonDC where he will play Kevin Anderson after the South African beat Jack Sock by the same score.
Spanish fourth seed Garbine Muguruza fine-tuned her preparations for this month's U.S. Open by crushing Simona Halep 6-1, 6-0 in the Cincinnati Open final on Sunday.
Former men's champion Mats Wilander believes third seed Muguruza now looks like the most likely champion, having not dropped a set and thrashing Maria Sharapova on Wednesday.
The 19-year-old beat the Japanese wildcard 6-2, 6-2 to set up a showdown with former US Open champion Sam Stosur, who downed American teenager Madison Keys 6-1, 6-2 in the other semi at the $250,000 event on the hard courts in Osaka.
Images from Day 4 of the 2023 Australian Open, at Melbourne Park.
Simona Halep's powers of recovery will be put to the test on day eight of the Australian Open on Monday when the world number one meets Japan's Naomi Osaka in a tricky fourth round clash.
He leads the men's seedings ahead of defending champ Roger Federer, with Bulgarian Grigor Dimitrov seeded third.
Lindsay Davenport hailed Serena Williams for delivering a 'powerful message' that shows it is possible to 'pursue personal goals even when you're a mum'.
Security worries could create a tense atmosphere at the French Open this year after a bomb attack on a British concert hall killed 22 people, French tennis player Lucas Pouille said.
A look at the records of Czech Republic's Karolina Pliskova and Japan's Naomi Osaka before their semi-final match at the Australian Open on Thursday (prefix number denotes seeding):
The 37-year-old has enjoyed a renaissance season that has seen her reach the Australian Open and Wimbledon finals and sit just one victory away, against American compatriot Sloane Stephens, from playing for the US Open title for the first time since 2002.
Top seed Serena Williams and her older sister Venus led a foursome of American women into the Australian Open fourth round on Saturday.
Badosa beats Fernandez; Swiatek, Halep storm into quarter-finals
Images from Day 5 of the 2023 Wimbledon Championships on Friday.
Photos from matches played at the US Open in Flushing Meadows on Sunday
Since that moment, Maria Sharapova has looked virtually unbeatable
'I will put everything I have Saturday on the court'
World No 1 Serena Williams has tormented Maria Sharapova for over a decade
Serena Williams has defeated her compatriot in four straight matches since a defeat in the quarter-finals of the 2013 Australian Open.
World number ones Serena Williams, aiming to complete the first calendar-year Grand Slam in 27 years, and Novak Djokovic have been named the top seeds for the US Open championships starting on Monday in New York.