Carlos Alcaraz dropped the opening set but beat Jaime Faria 4-6, 6-0, 6-3, 6-2 on Wednesday night to move into the US Open third round.
Eight straight games turned the match after the defending champion was broken in the first set; Alcaraz said he settled down, stopped rushing points and returned to longer rallies.
Four months out with a right wrist injury shaped his view of the extra set, with Alcaraz saying the longer match helped test his body after missing the French Open and Wimbledon.
No. 2 seed Alcaraz said he is pain-free and hitting his forehand without restrictions, while Daniil Medvedev called him a top title favorite if his wrist holds up deeper into the tournament.
The 23-year-old owns 7 major titles and has won 16 straight Grand Slam matches, after taking last year's US Open and this year's Australian Open.