MIAMI (AFP) - Top seed Daniil Medvedev moved within one victory of reclaiming the world number one ranking by advancing to the ATP and WTA Miami Open quarter-finals, defeating American Jenson Brooksby 7-5, 6-1 on Tuesday (March 29).

Australian Open runner-up Medvedev rallied from 3-5 down in the first set to win 10 of the last 11 games and advance after 80 minutes.

"It wasn't easy at the start but when he didn't convert a double break point I managed to find another gear, playing better, and I managed to get on top," Medvedev said.

"I tried to keep my energy up. At the start it wasn't enough so I pumped myself up and tried to close it out as soon as possible."

Medvedev will next play either defending champion Hubert Hurkacz, the eighth seed from Poland, or South African Lloyd Harris.

A victory to reach the semi-finals would move the 26-year-old Russian back into the top ranking on Monday after he surrendered the spot to Novak Djokovic.

Medvedev matched his best Miami showing, a last-eight run in 2021, by defeating 39th-ranked Brooksby.

"Jenson has the potential to be a top player. He's playing better than his ranking," Medvedev said. "But I knew it wouldn't be easy on this surface. It doesn't suit my game perfectly." World number four Alexander Zverev's push to land his first title of the year moved a step closer as the German second seed reached the quarter-finals by beating Australian Thanasi Kokkinakis 6-4, 6-4.

Kokkinakis, who along with compatriot Nick Kyrgios, won the Australian Open doubles title, appeared to struggle with a chest injury in the second set and Zverev moved through the gears when it mattered to set up an encounter with Norway's Casper Ruud for a place in the semi-finals.

"He is in the fourth round for a reason so I'm just happy to come through," Zverev said. "I won my first Masters event here and reached my first quarter final so this tournament has been good to me." Kokkinakis hit eight aces but was unable to break the German's serve.

Ruud made light work of British number one Cameron Norrie, winning 6-3,6-4.

Kyrgios has fiery exit

Kyrgios lost his head in the Miami heat and spent his fourth-round match delivering a blistering verbal assault on Brazilian match umpire Carlos Bernardes before crashing out 7-6 (7/3), 6-3 in the last 16 to Italy's Jannik Sinner.

The Australian became involved in a running war of words after the walkie-talkie of Bernardes went off mid-point in the first set.

Kyrgios was seething with Bernardes, calling him "an absolute clown" before raging: "This is one of the biggest tournaments and you guys can't do your job. It's embarrassing."

The Aussie also snapped: "You wonder why no one watches this sport. It's a laughing stock."

Kyrgios refused to let his anger lie and, having already received a code violation for an audible obscenity, was hit with a point penalty at 5-3 in the first set tie-break for unsportsmanlike conduct after appearing to talk with a friend who was sitting courtside.

A game penalty was then issued at the start of the second set after Kyrgios shattered his racket.

Kyrgios, who said earlier this week that he was at "peace" with himself on and off the court, was also involved in a bizarre incident on the Grandstand court when a fan ran onto the playing surface and managed to get a selfie with him.

"I knew Nick was trying to raise his level," Sinner said. "But I just tried to stay calm somehow and be in the present moment."

The ATP fined Kyrgios US$25,000 (S$33,905) on Tuesday for smashing his racket and an audible obscenity during his match at Indian Wells against Rafael Nadal.