Novak Djokovic faced a series of obstacles in the Miami Open final: a delay of more than five-and-a-half hours before the match, an eye infection and a slippery court due to high levels of humidity following the rain.

But the largest roadblock was the youth and power of 6-foot-4, 19-year-old phenom Jakub Mensik, who outdueled the 37-year-old Serbian 7-6 (7-4) 7-6 (7-4) to win his first ATP title.

Ranked 54th entering the tournament, the Czech Republic teenager plowed through Djokovic with poise and a booming serve. He collected 14 aces and got broken only once. Mensik bashed a service winner on match point and fell on his back.

"You're the one I idolised when I was young," Mensik said to Djokovic during the ceremony after the match that lasted two hours three minutes.

"I started playing tennis because of you."

Mensik's victory spoiled the party for Djokovic, who was seeking his 100th career title and a record seventh in Miami.

"This is a joyous moment for him and his family — an unbelievable tournament, first of many," Djokovic said.

"It hurts me to admit it, you were better. In the clutch moments you delivered the goods. For a young player like yourself, this is a great feature."

The Miami crowd pulled hard for Djokovic, who hadn't played there since 2019.

But the men's leader with 24 grand slam titles seemed compromised by his eye issue, with redness seen under the eyelid. Djokovic applied eye drops during two changeovers in the first set.

During the set, he also slipped twice on the court. The humidity reached 90 per cent after hours of rain disrupted the card. Sweating profusely, Djokovic asked the umpire for a bucket of sawdust to sprinkle on his wet grip.

Mensik was playing his first ATP 1000 final and was not quite two years old when Djokovic won his first Miami Open title in 2007.

The Czech had lost to Djokovic in a three-setter last October at the Shanghai Masters but the youngster said before the match he had played too nervously.

There was more fearlessness this time, going up 3-0 with an early break but Djokovic levelled for 4-4.

In the first-set tiebreak, Mensik executed a leaping backhand volley winner and Djokovic muffed a routine forehand drop shot into the net to fall behind 5-0. On set point, Mensik slugged an overhead smash for a winner.

The match was scheduled for 3pm but the players didn't take the court until 8.37pm due to rain and organisers deciding on completing the women's doubles final, which Mirra Andreeva and Diana Shnaider won by beating Cristina Bucsa and Miyu Kato 6-3 6-7 (5-7) 10-2.