Carlos Alcaraz reached the last-16 stage of the Swiss Indoors Basel by beating Jack Draper in three sets on Monday.
The number one seed lost the opening set but responded to take the following two and win 3-6 6-2 7-5.
Alcaraz dominated at the net, winning 30 of 39 points to edge out his opponent after more than two hours.
Elsewhere, at the Vienna Open, fourth seed Taylor Fritz overcame Yoshihito Nishioka in another three-set thriller.
Nishioka took the opener, and Fritz was staring down the barrel in a second-set tie-break before trailing by a break in the decider.
However, the American won the final five games to advance 6-7 (4-7) 7-6 (9-7) 6-3.
The comeback boosted Fritz's chances of making the ATP Finals, trailing Felix Auger-Aliassime by 315 points in the Race to Turin.
Third seed Andrey Rublev found life far easier as he beat Diego Schwartzman 6-4 6-1.