Novak Djokovic on Monday faces his biggest challenge so far at Wimbledon in his quest for a record-breaking 25th Grand Slam as Alexander Zverev targets his first quarter-final at the All England Club.
Former champion Elena Rybakina is back on court, while diminutive giant-killer Yulia Putintseva aims for another upset against former French Open champion Jelena Ostapenko.
In early fourth-round action, Italian 25th seed Lorenzo Musetti tamed big-serving Frenchman Giovanni Mpetshi Perricard, coming from a set down to win 4-6, 6-3, 6-3, 6-2.
Lucky loser Mpetshi Perricard had been broken just once in three rounds at Wimbledon but Queen's finalist Musetti found the key on Court No. 2, breaking five times as his opponent racked up 42 unforced errors.
"It's tough for me to get emotional but I think today I will," said the Italian. "I've been dreaming of this moment since I was a kid.
"It's such a big day for me and I'm really happy and proud of this win against a tough opponent. I struggled a little at the beginning against a big serve. I'm a little bit shaking still but at the end it's a really phenomenal day for me."
Seven-time champion Djokovic comes up against Danish 15th seed Holger Rune, 21, a man who has beaten him twice.
Djokovic -- seeking to equal Roger Federer's record of eight Wimbledon men's titles -- had surgery last month to repair a torn medial meniscus suffered during the French Open.
The 37-year-old, seeking to become the first player, man or woman, to win 25 majors, has dropped a couple of sets but has largely looked untroubled so far.
Rune, by contrast, was forced to dig deep in his third-round match against Quentin Halys after trailing by two sets to love.
"He looks to me a player that is ready for big things. He's a spectacular player, no doubt," said Djokovic. "He's a very tricky opponent.
"When it comes to competing, obviously we both have that fire. I'm sure on Monday we'll see a lot of fireworks on the court."
Alexander Zverev, the fourth seed, is desperate to shake off his nearly-man tag and win a first Grand Slam.
The German reached the final at Roland Garros last month -- his second Grand Slam final -- though his record at Wimbledon is modest, with the fourth round being his best showing to date.
The former world number two has not been broken once at Wimbledon this year.
Standing in his way is American 13th seed Taylor Fritz, who arrived at the All England Club on a high after winning the Eastbourne International on grass.
After ousting world number one Iga Swiatek in the third round, Putintseva faces Jelena Ostapenko for a place in the last eight.
The world number 35 fought back to stun Swiatek 3-6, 6-1, 6-2 and end the Polish star's 21-match winning streak on Saturday.
Putintseva's victory continued a superb grass-court season for the 29-year-old, who won the Birmingham Classic last month.
The Russia-born Kazakh player has reached the quarter-finals of the French Open and US Open, but had never been beyond the second round at Wimbledon.
"Last year I won no matches on grass. I mean, entering a tournament like Wimbledon, when you have five consecutive wins on grass, it's pretty good. You feel this surface much better," Putintseva said.
Ostapenko won the French Open in 2017 and reached the Wimbledon semi-finals a year later, but has struggled to hit those heights since then.
Wimbledon organisers said they were confident of finishing the tournament on time despite forecasts of more wet weather.
There were only two dry days in the first week and some events are already behind schedule following numerous delays.
"We now have an extra day (middle Sunday), we've got the two roofs, so in terms of resilience to get through the Championships, we're confident we can still do that despite the continuing variability of the weather," said chief executive Sally Bolton.
