Holger Rune battled back from a set down to beat Sebastian Baez 4-6, 6-1, 6-2 on Wednesday to reach the Barcelona Open quarterfinals.
The world number 13 pulled out of Monte Carlo with food poisoning last week but roared back to defeat his Argentine opponent in three sets on the clay after a troubled opening.
Baez broke in the first game, consolidating for a 2-0 advantage and served it out to claim the first set, with Rune committing 15 unforced errors to 10 winners.
However, the Dane broke three times in the second set to get back on track and did the same again in the decider, converting his third match point.
Earlier, Frenchman Arthur Fils breezed past Spain's Pedro Martinez in straight sets 6-3, 6-2.
Ranked 14th in the world, Fils conceded just one break point in the match, which the 20-year-old saved.
Later on Wednesday, defending champion Casper Ruud faces Hamad Medjedovic and 2024 runner-up Stefanos Tsitsipas takes on Sebastian Korda in other second round matches.