Top seed and reigning champion Carlos Alcaraz dished out a bagel as he continued his outstanding form with a straight-sets victory over Dusan Lajovic to ease into the Miami Open fourth round on Sunday.

Alcaraz, who triumphed at last week's Indian Wells Open, beat the 76th-ranked Serbian 6-0 7-6 (7-5) in one hour and 32 minutes.

The 19-year-old Spaniard hit 26 winners compared to Lajovic's eight, while Alcaraz also sent down three aces on a 75 per cent first serve percentage.

Alcaraz won the first frame to love in 32 minutes, registering his fourth career bagel at ATP Masters 1000 level, equaling the most by a teenager alongside Rafael Nadal.

The world number one will face 2023 Australian Open semi-finalist Tommy Paul in the fourth round after the American got past 20th seed Alejandro Davidovich Fokina 6-3 7-5.

Third seed and 2022 Miami Open finalist Casper Ruud blew a first-set lead to lose 3-6 6-4 6-4 to Botic Van De Zandschulp.

The Dutchman improved his head-to-head record against Ruud to 3-1 with his first-ever top five win, with the Norwegian left to lament converting only two of 15 break points.

Ninth seed Taylor Fritz progressed into the fourth round with a 6-4 6-4 win over Denis Shapovalov, improving his head-to-head record against the Canadian to 4-5. Fritz committed only eight unforced errors and did not face one break point.

Jannik Sinner maintained his excellent hard-court form with his 18th win this season on the surface, as he defeated Grigor Dimitrov 6-3 6-4 in one hour and 28 minutes. The Italian 10th seed will be Andrey Rublev in the next round.

Sixth seed Rublev needed less than an hour to get past Miomir Kecmanovic 6-1 6-2, while compatriot Daniil Medvedev advanced via a walkover against Alex Molcan due to a right hip injury.

Seventh seed Holger Rune cruised past Diego Schwartzman 6-4 6-2, while Finland's Emil Ruusuvuori got past Taro Daniel 6-3 7-6 (7-3).