Carlos Alcaraz became the youngest Miami Open men's champion as the teenage Spaniard continued his rapid rise by fending off world number eight Casper Ruud.

A 7-5 6-4 victory in Sunday's final gave 18-year-old Alcaraz the third ATP singles title of his career, after winning the 2021 Croatia Open and the Rio Open in February this year.

Alcaraz's maiden Masters 1000 title saw him secure Miami glory even earlier than Novak Djokovic, who was 19 at the time of his 2007 triumph.

"I have no words to describe how I feel – it feels so special to win my first Masters 1000 here in Miami," Alcaraz said.

While he got the job done in the end, there was far from a smooth start for Alcaraz, who lost the first three games of the opening set as Ruud grabbed the early break.

Down 4-1 in that first set, Alcaraz then rattled off three consecutive games to tie it back up, and after breaking again to go up 6-5, he held his nerve to save a break point and move ahead in the contest.

Ruud had issues dealing with Alcaraz's first serve all match long, but it was most dominant in the first set, the Spanish player winning 76 per cent when landing his first serves, while Ruud was down at 54 per cent.

Alcaraz flipped the script in the second set and jumped out to a 3-0 lead with a double break. Ruud was able to get one break back, but he never threatened the rest of the way as Alcaraz closed it out in style, conceding only two points from his last three service games.

Speaking on the court after his win, Alcaraz was overjoyed as he acknowledged a large contingent of support in the crowd, including coach Juan Carlos Ferrero.

"I have my whole team with me, and my family… this is the second tournament that they've all been here with me," he said.

"Thank you to my team, I'm glad to have my father here with me and to be able to share this moment with my family."

Touching on some of his strategy, Alcaraz said the plan was to try and avoid Ruud's dominant forehand as much as possible.

"I knew Casper is playing unbelievable, and has a big forehand, so I tried to play to his backhand first, and attack all the time," he said.

"I'm always trying to attack, and not let him dominate the match with his forehands down the line – that was a pretty big key for me."

With the win, Alcaraz becomes the world number 11, and does not turn 19 until next month.