San Francisco Frontiers - Alcaraz tackles Shelton for spot in French Open quarters as Swiatek faces old foe

Top seed Aryna Sabalenka will face past semi-finalist Amanda Anisimova, while fourth-ranked Jasmine Paolini is in action against one-time world number three Elina Svitolina.

Lorenzo Musetti, who has reached at least the last four in all the clay court Masters events this season, will tackle Barcelona Open winner Holger Rune as the competition heats up on both sides of the draw.

"Playing the defending champion, round of 16... centre court, that's a pretty cool opportunity, pretty cool experience, that not a lot of people get or see in their lifetime," said Shelton of facing Alcaraz.

"For me, I'm definitely going to enjoy it and go out there and see what I can do, because I'm... starting to see some of my best tennis.

"I like to think of myself as dangerous whenever I get to that place."

Alcaraz has won both of his previous meetings with the American in straight sets, but the Spaniard has shown some signs of fragility so far at Roland Garros, dropping sets in his last two matches.

In his second-round win over Fabian Marozsan, Alcaraz admitted he "couldn't handle" the 56th-ranked Hungarian's level at times as he lost the second set 6-4.

After winning his third round match against 69th-ranked Bosnian Damir Dzumhur on Friday, the former world number one said: "Today I honestly didn't enjoy it that much. I suffered quite a lot."

However, four-time Grand Slam winner Alcaraz has proved in the past he can battle through a sticky period and boasts an excellent record on clay this year, losing only once in the final at Barcelona either side of wins in Monte Carlo and Rome.

The architect of that sole defeat, Rune, will be in night session action for his match with eighth seed Musetti.

The Dane beat defending champion Alcaraz in straight sets in Catalonia, but the 10th seed has shown up-and-down form so far at Roland Garros, losing the opening set in two of his three matches so far.

Musetti also endured a blip in the last round as he dropped his first set of the tournament against Argentinian Mariano Navone.

"I think, again, as he (Musetti) said, he can't afford to give me the first set, and the same me, I can't afford to give him the first set like this," said Rune.

"(I'm) looking forward to that match, it's going to be hopefully a great battle."

Two more Americans complete the day's action on the men's side of the draw, with 12th seed Tommy Paul playing Australian Alexei Popyrin and 16th-ranked Frances Tiafoe facing Germany's Daniel Altmaier.

- Poker-face Swiatek -

Triple-defending champion Swiatek will face the lesser of two evils when she takes on 2022 Wimbledon winner Rybakina after the Kazakh emerged victorious against Jelena Ostapenko, who holds a remarkable 6-0 win/loss record over the Pole.

"Both matches are going to be a challenge. But let's see who wins," said Swiatek before discovering her last 16 opponent.

When asked if she had a preference between Rybakina and Ostapenko, the 23-year-old joked: "No... Am I a good liar? Let's say it doesn't matter, really.

"Oh, my God. I couldn't play poker."

But Swiatek's record against Rybakina is only marginally better, with the players being tied at 4-4, though the fifth side has won both meetings between the two this season.

Their last match on clay came in Stuttgart in 2024, with 12th-seed Rybakina claiming victory in three sets.

World number one Sabalenka has dropped just 10 games in reaching the fourth round, and will meet her first seeded player of the tournament against American Anisimova.

Should the Belarusian advance to the quarter-final stage -- where she surprisingly lost last year to Russian teenager Mirra Andreeva -- it is likely she will there face Olympic champion Zheng Qinwen.

The Chinese eighth seed will also take to the court on Sunday to do battle with 18th-ranked Russian Liudmila Samsonova.

Last year's runner-up and current Italian Open champion Paolini will kickstart the day's action on Court Philippe Chatrier against four-time quarter-finalist Svitolina.

E.Walker--SFF