Alcaraz, who turns 19 next month, showed just why many believe he is currently the hottest young prospect in men’s tennis with a 7-5, 6-4 victory.
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Only two men have won titles at this level at a younger age – Michael Chang, who was 18 years and five months old when he won Toronto in 1990, and Rafael Nadal, 18 years and 10 months when he claimed the Monte Carlo crown in 2005.
Alcaraz dropped just one set on the way to his Miami crown and now will head off to compete on his preferred surface of clay buoyed by the biggest win of his career.
Much is expected of Alcaraz whose passionate, all-energy displays in the latter stages of the Miami Open energised the Florida crowd.
It was the more understated Norwegian, 23, however, who made the better start by breaking early and keeping the pressure firmly on his precocious opponent.
Despite the majority of the crowd backing the Spanish player, he was unable to take a break opportunity at 3-1 with Ruud proving he possesses the kind of mental strength to thrive in such high pressure situations.
Yet when another chance came to pierce the world number eight’s service game, Alcaraz, who reached the last four in Indian Wells last month, grabbed it before holding his own serve to put a lively first set firmly back in the balance at 4-4.
A blistering forehand set up two more break points and although Ruud saved the first, he then hit wide to put Alcaraz in the driving seat to land the opening set.
Two breaks at the start of the second set further cemented Alcaraz’s dominance, the teenager racing into a 3-0 lead which was too tall a mountain for the combative yet ultimately outclassed Ruud.