INDIAN WELLS, United States, March 13, 2024 (BSS/AFP) - Defending champion Carlos Alcaraz and Italian rival Jannik Sinner remained on course for a semi-final showdown after cruising into the last eight of the ATP-WTA Indian Wells Masters on Tuesday.

Alcaraz sailed into the last eight as he took revenge on Hungary's Fabian Marozsan with a 6-3, 6-3 victory.

In-form Sinner meanwhile booked his last eight berth with a 7-6 (7/4), 6-1 defeat of Ben Shelton.

Sinner's win was his 18th straight victory dating to late last season, leaving him three wins away from his third title of the season after winning the Australian Open and Rotterdam.

"I played really well in the tight moments," the 22-year-old world number three said as he lines up against Czech Jiri Lehecka in the quarters.

"I knew I would not get much rhythm from him. I can be proud of how I played. The wind didn't make it easier but I tried to stay positive and it worked out."

Sinner could face Spain's reigning Wimbledon champion Alcaraz in the semi-finals in California in what would be the latest instalment of a burgeoning rivalry.

The duo fought an epic US Open quarter-final in 2022 and met in the semi-finals at Indian Wells and Miami Masters events last season.

Alcaraz must navigate a quarter-final against sixth seed Alexander Zverev before any meeting with Sinner. Zverev reached the last eight after defeating Alex de Minaur 5-7, 6-2, 6-3 in two and three-quarter hours.

Alcaraz had a score to settle with the 58th-ranked Marozsan after losing their only other meeting at last year's Rome Masters.

Alcaraz never let his opponent into the fourth-round match, breaking twice in the opening set and winning 12 of the first 13 points of the second.

The top seed reeled off 22 winners in 75 minutes to race into the quarter-finals.

After a slow start this season and an ankle roll several weeks ago in Brazil, the 20-year-old appeared on course to continue his chase to a possible second title here.

- 'Almost perfect' -

"I was nervous before the match, I'm not going to lie," Alcaraz said.

"I was playing someone who beat me when I had no chances in the Rome match."

But he walked off a winner completely pleased with his performance.

"Let's say (it was) almost perfect. I can play better.

"But I'm really happy with the way I approached the match, the way that I played, and my feelings."

Elsewhere Tuesday, Greek Stefanos Tsitsipas failed to reach a second career quarter-final here, with the 11th seed losing 6-2, 6-4 to rising Czech youngster Lehecka.

The upset was the youngster's second in succession after dispatching fifth seed Andrey Rublev in the previous round.

Tsitsipas, whose form has been modest so far this season, achieved the last eight during his 2018 debut at the Tennis Garden but has yet to duplicate that effort.

He was ousted in 78 minutes by number 32 Lehecka, winner of the January Adelaide title and now heading into the first Masters quarter-final of his career.

In the women's fourth round, Caroline Wozniacki won a battle of returning tennis mothers, defeating Anelique Kerber 6-4, 6-2.

Both of the over-30 pair of former number one players and Grand Slam champions are back competing on the Tour after giving birth.

"Things were going a bit my way and she was struggling a bit with her back," Wozniacki said. "I'm just happy I won.

"This will be my first quarter-final since my three-and-a-half year (maternity) break.

"To be back playing is a special feeling."

Dubai champion Jasmine Paolini lost 7-5, 0-6, 6-3 to Anastasia Potapova while Ukrainian Marta Kostyuk beat Anastasia Pavlyuchenkova 6-4, 6-1 to reach the last eight.