World number two Carlos Alcaraz came back from a break down in the second set to defeat Ethan Quinn 6-2, 7-6 (8/6) and reach the Barcelona Open last 16 on Tuesday.
The home favourite, who triumphed at the Monte Carlo Masters last week, stormed through the first set but Quinn, ranked 126th, battled valiantly in the second.
Alcaraz has endured an inconsistent start to the year, crashing out of the Miami Open at the first hurdle in March, as he prepares for his French Open title defence.
The 21-year-old is aiming for a third triumph on the clay in Barcelona, after lifting the trophy in 2022 and 2023. He was unable to participate in the last edition because of injury.
"Last year it was very painful not to be here, so I am very happy to be able to come back and play here again, and more so to win," Alcaraz told TVE.
"I made some mistakes, I found it hard to maintain (the right) level, but I am happy to have solved the problems that came in the second set, and to end up winning in two sets."
Alcaraz saved all five break points he faced in the first set, breaking Quinn in the third and fifth games for a 5-1 lead.
The Spaniard failed to convert a set point in the seventh game but did so at the third time of asking on his serve after opening up a triple set point.
The second set was topsy-turvy, with both players exchanging breaks on three occasions, forcing a tie-break.
Alcaraz saved a set point before dispatching Quinn with a drop shot to claim victory.
WINNING START FOR DEFENDING CHAMP
Earlier, defending Barcelona Open champion Casper Ruud sailed into the last 16 with a 6-4, 6-3 win over Daniel Elahi Galan.
The world number 10, targeting his first trophy of the season, blew away his Colombian opponent hitting 25 winners and without facing a break point.
Norwegian Ruud put heavy pressure on Galan's serve before securing the only break of the first set in the 10th game.
In the second set Ruud broke for a 4-2 lead and served it out.
"I'm happy to be back in Barcelona and get a straight-sets win," said Ruud.
"One year ago, I had one of the best weeks of my life, so the memories come back."
France's Arthur Fils beat Spaniard Pablo Carreno Busta 7-6 (8/6), 6-3, while last year's runner-up Stefanos Tsitsipas crushed giant American Reilly Opelka 6-2, 6-2.