Carlos Alcaraz passed a "test of fire" to breeze into the Madrid Open last 16 with a straight sets victory over Thiago Seyboth Wild on Sunday, while Aryna Sabalenka staved off teenager Robin Montgomery to progress in three sets.

Double defending champion Alcaraz came through 6-3, 6-3 and will face last year's runner-up Jan-Lennard Struff in the next round after another impressive showing before adoring fans on home soil.

World number three Alcaraz, 20, missed a month prior to Madrid with a forearm issue but returned to crush Alexander Shevchenko in the second round and looks in fine shape ahead of the French Open, the second Grand Slam event of the season.

Still wearing a protective sleeve on his right arm, he had far too much for Seyboth Wild, who had ousted 28th seed Lorenzo Musetti.

German fourth seed Alexander Zverev, the 2018 and 2021 Madrid champion, made the last 16 with a 6-4, 7-5 win over Canada's Denis Shapovalov.

Andrey Rublev came back from 5-0 down in a first set tie-break to beat Alejandro Davidovich Fokina 7-6 [12/10], 6-4 in a tense affair.

Women's world number two Sabalenka scraped past plucky 19-year-old Montgomery 6-1, 6-7 [5/7], 6-4 in a two-and-a-half hour tussle.

Sabalenka broke twice for a 5-1 lead against Montgomery, who steeled herself and battled well in the final game, saving three set points before Sabalenka sealed it.

World number four Elena Rybakina eased to a 6-1, 6-4 win over Egypt's Mayar Sherif to reach the last 16.

Mirra Andreeva defeated Wimbledon champion Marketa Vondrousova 7-5, 6-1 to return to the last 16 for the second year running.

The Russian, who turns 17 on Monday, won 25 points to nine in the second set against the world number seven from the Czech Republic. (AFP)