Novak Djokovic is two wins away from capturing a 100th career title after beating Sebastian Korda 6-3 7-6(4), and world number one Aryna Sabalenka cruised into her first Miami Open final with a 6-2 6-2 victory over Jasmine Paolini on Thursday.

Djokovic let out a triumphant roar after sending down an ace on match point as the 37-year-old's former rival and now coach Andy Murray jumped out of his seat to do the same.

The Serbian 24-times Grand Slam champion trailed Korda 5-2 in the second set but broke the American as he served at 5-3 and his precise and powerful serving carried him to the finish.

"I've been serving great the entire tournament but particularly today I needed it in the second to try to come back," Djokovic told Tennis Channel.

"In the tiebreak, a couple of points really decided the winner, 5-4 service winner, ace at 6-4 to finish off the match. So I'll take that as the highlight."

Victory ensured that Djokovic, who turns 38 in May, became the oldest ATP Masters 1000 semi-finalist, surpassing Roger Federer, who made the final four at Indian Wells and Miami aged 37 years and seven months in 2019.

The match was originally scheduled for Wednesday but postponed under ATP rules aimed at avoiding matches dragging on into the early hours of the morning.

Fourth seed Djokovic, gunning for a record seventh Miami Open title, will face 14th-seeded Bulgarian Grigor Dimitrov in the semi-finals on Friday.

Unseeded Czech Jakub Mensik was a 7-6(5) 6-1 winner over 17th-seeded Frenchman Arthur Fils and will meet American Taylor Fritz in the semis after he outlasted Italian 29th seed Matteo Berrettini 7-5 6-7(7) 7-5.

Third seeded Fritz saw six match points come and go in the second set but converted on his seventh opportunity in the decider to put away Berrettini.

"There's two options, get frustrated about it, lose and then be even more frustrated about all the chances I blew, or regroup and get the win," Fritz said.

"Now I can sleep tonight."

PEGULA ENDS EALA'S RUN

On the women's side, Sabalenka won 77% of her first-serve points, fired down six aces, saved all four break points she faced and converted four of her five break point chances against Italian sixth seed Paolini during the 71-minute match.

The Belarusian top seed, who resides in South Florida and arrived in Miami fresh off a runner-up finish at Indian Wells, has not dropped a set in her five matches.

Up next for Sabalenka will be American fourth seed Jessica Pegula, who ended the fairytale run of Philippine wildcard Alexandra Eala 7-6(3) 5-7 6-3.

"It's nice to know I can win these big matches in really clutch, pressure moments and come out on top," said Pegula, who will compete in her sixth WTA 1000 final.

"One of the people who does it better than me is Aryna. I'm going to have a big battle."

Pegula battled back from 2-5 down to win the opening set and was up a break in the second before 19-year-old Eala came back to level the match despite twisting her ankle during a point.

But Pegula's experience shone through in the decider and she prevailed in a thriller that finished well past midnight, with the 31-year-old writing, "I'm tired" on a camera lens.

Eala, who beat three Grand Slam champions during her run, blew kisses to a small crowd that gave her a standing ovation after sharing a warm exchange with Pegula at the net.