World number one Carlos Alcaraz announced the start of his Miami Open title defence in emphatic fashion, losing just two games in a comprehensive win over Facundo Bagnis.
The US Open champion, 19, needed 65 minutes to complete a 6-0 6-2 victory against the Argentine, ranked 100.
The Spaniard, who triumphed at Indian Wells last week, has lost just one of his 16 matches this year.
He must defend his title in Miami to stay as the world's top ranked player.
That is despite the absence of Novak Djokovic - who is not permitted to enter the US because of his Covid-19 vaccination status - as he requires the 1,000 ranking points that would accompany success to stay ahead of the Serb.
"I knew that I needed to be focused for my first match," said Alcaraz.
"To start a new tournament is never easy. 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."
Alcaraz was forced to miss the first Grand Slam of the year at the Australian Open because of injury - however he is doing his best to make up for lost time.
Unstoppable at Indian Wells last week - his second title of the season after winning in Buenos Aires in February - he announced his arrival in Miami by winning the first 11 points against a helpless Bagnis.
Bagnis could not get close, failing to win a point on the Spaniard's serve, as Alcaraz took the first set in 24 minutes.
It was the first time the teenager had recorded a 'bagel' - winning a set without conceding a game - in an opening set at an ATP Masters 1000 level event.
The crowd got behind Bagnis as he offered a response with a break of serve to level at 2-2 in the second, but Alcaraz then rattled through four successive games to seal progress to round three.
He will play Dusan Lajovic, who beat Britain's Andy Murray on Wednesday, or Maxime Cressy next as he continues his bid to become the youngest man to complete the 'Sunshine Double' - winning Indian Wells and Miami in the same calendar year.
In the women's draw, Canadian 22-year-old Bianca Andreescu, who ended British number one Emma Raducanu's challenge earlier this week, came back to defeat world number 10 Maria Sakkari 5-7 6-3 6-4.
France's world number four Caroline Garcia and Tunisian Ons Jabeur, ranked fifth, were both also beaten.
Garcia lost 6-2 6-3 to Romanian Sorana Cirstea in the second round.
Jabeur suffered a surprise 6-2 6-2 defeat by 22-year-old Russian qualifier Qualifier Varvara Gracheva, as the former world number two continues her recovery following a knee injury.