Defending champion Carlos Alcaraz through to fourth round in Miami

The 19-year-old Spaniard, who returned to the world number one spot last week as he lifted the trophy in Indian Wells, emerged with a 6-0 7-6 victory from a contest lasting just over 90 minutes.

The first set took just 32 minutes as Alcaraz broke his Serbian opponent in the opening game and did not let up en route to a whitewash.

In the second he suffered his first break of serve at 5-4 before going on to secure victory via the tie break.

Alcaraz said in quotes on atptour.com: "I feel fast on court, I am moving well.

"I am happy with the variety I am playing (with). Lots of shots. I am enjoying every single second out there."

Alcaraz, who will prevent Novak Djokovic from replacing him at the top the world rankings if he retains the Miami title, will next face Tommy Paul, a 6-3 7-5 victor over Alejandro Davidovich Fokina.

Third seed Casper Ruud was defeated in an upset at the hands of 27-year-old Botic van de Zandschulp in three sets.

The Dutchman won in just under three hours of play, saving 13 from 15 break points en route to a 3-6 6-3 6-4 win.

The victory for the 26th seed was his first against a top-five player and he will go on to play the Finnish 23-year-old Emil Ruusuvuori in the fourth round.

Meanwhile, sixth seed Andrey Rublev made tidy work of Serbian Miomir Kecmanovic, winning 6-1 6-2 in just 58 minutes.

The 25-year-old Russian progresses after a dominant display and will next play 10th seed Jannik Sinner, who beat Grigor Dimitrov in two sets 6-3 6-4.

The 21-year-old Italian was too strong for Dimitrov, beating him in just under 90 minutes.

Holger Rune cruised into the fourth round with a 6-4 6-2 victory over Diego Schwartzman.

The 19-year-old will have a tough task next round facing American Taylor Fritz, who demolished Canadian Denis Shapovalov in straight sets.

Fritz won 82 percent of points on his first serve and 81 percent on his second while a frustrated Shapovalov hit 12 aces but conceded seven double faults and failed to break the American's serve.