World No 1 Carlos Alcaraz made an emphatic start to his Miami Open title defence, defeating Argentina's Facundo Bagnis 6-0, 6-2 on Friday. The 19-year-old Spaniard, the youngest ever player to top the rankings, is looking to complete the 'sunshine double' after beating Daniil Medvedev in last week's Indian Wells final. Alcaraz made a blistering start winning the first 11 points of the match, with the 33-year-old Bagnis having no answer at all to the teenager's powerful serve. There was a loud cheer from the crowd at Hard Rock Stadium when Bagnis, who has never beaten a top 20 ranked player, held serve in the second set and then broke Alcaraz to make it 2-2. But that was a brief moment of respite for Bagnis rather than any shift in momentum and Alcaraz had no further problems as he blasted his way to victory in just 65 minutes. "To start a new tournament is never easy, different conditions. I have to be ready to get used to these new conditions, but I was really focused on the match from the beginning, and I'm happy with the way that I played," said the Spaniard. Alcaraz needs to win in Miami to maintain his top spot in the rankings. After his win in Miami last year, Alcaraz boldly predicted he was ready to win a Grand Slam and he returns now having achieved that goal and, he concedes, as a different man. "I grew up a lot since last year. It has been a great year for me as a player, as a person as well. I learned a lot of things, not only on court, also off the court, as well," he said. His whirlwind year caught up with him physically - he had to miss January's Australian Open with a leg injury - and the Spaniard says he is now more careful about his physical condition. "I have to take care about myself a little bit more off the court, taking care about going early to bed, to rest better, eat well, take care of myself off the court. That's the most important thing for me," he said.