Britain's Andy Murray battled past David Ferrer in a gruelling final to win his second Miami title and regain the world number two ranking.
The Scot, 25, saved a match point on his way to winning 2-6 6-4 7-6 (7-1) for his ninth Masters title.
Murray recovered from losing the first five games and survived a Hawk-Eye call at match point down in the final set.
The victory brought a 26th career title and ensured he will pass Roger Federer in the new world rankings on Monday.
It was also Murray's first win at the elite Masters level since be beat Ferrer in Shanghai at the end of 2011, although he has since won Olympic gold in London and his first Grand Slam title at the US Open.
Sunday's final was played in brutal humidity, which contributed to an unusually high 14 breaks of serve and left both men visibly struggling in the latter stages.
"It was such a tough match," said Murray, who was ranked number two for three weeks in 2009, the same year he first won in Miami.
"It could have gone either way, both of us were struggling physically at the end. It's so tough against him. He has a great attitude, he's a great fighter. I am sure we will have more tough matches in the future."
Ferrer, 31, was looking to win only his second Masters title and made a superb start with five straight games as the Murray serve faltered, a double-fault giving up the set as he was broken for the third time to love.
The Spaniard recovered an early break in the second set to level at 4-4 and Murray looked rattled, at one stage arguing with the umpire after being warned for slow play.
Ferrer had sight of the finish line but then played a poor game, gifting the advantage back to Murray with four errors, and the Briton enjoyed a rare easy service game to level after one and a half hours.
The conditions really began to take their toll in the final set. and Ferrer had the trainer on to massage his legs at several changeovers, much to Murray's annoyance.
After six successive breaks, it felt like Ferrer had taken a major step towards the title when he held for 4-3, but Murray responded with a hold of his own and another break, only to stumble when serving for the match.
Ferrer worked his way to a 6-5 lead and earned a match point, but a flashing forehand from Murray landed desperately close to the baseline and, rather than see if Murray would hold his nerve for the following shot, Ferrer called for a Hawk-Eye challenge.
It proved to be the biggest call of the match as the replay showed the ball to catch the back of the line, and Murray held moments later to force a deciding tie-break.
Looking exhausted between points but the livelier during them, Murray dominated from the moment he won the opening point on a net cord.
By the time he moved 5-1 clear, Ferrer was in such difficulty that he briefly collapsed to the ground with cramp, and Murray put him out of his misery soon after with a backhand winner on his first match point.
Asked afterwards about the match point he saved, thanks in part to the challenge, Murray said: "That's the beauty of the challenge system; in some matches that would have been over but luckily it just dropped in."
He added: "I just managed to fight well in the end. They were incredibly difficult conditions, very windy, extremely humid and hot.
"I served poorly and if I'd served better, I could have made things easier for myself. That's something I'll need to do better during the clay season."