Dominic Thiem held his nerve to battle past Jaume Munar in three sets to progress to the quarter-finals of the Rio Open.
The Austrian was stunned by the 99th-ranked Spaniard early as Munar managed to take the first set in a tie-break.
However, the more-experienced Thiem was able to rally in the second, overwhelming his 22-year-old opponent on both ends of serve before running away with it in the third.
The 6-7 (5-7) 6-3 6-4 victory sees Thiem go through to a quarter-final match against Italian qualifier Gianluca Mager.
Mager booked his place in the last eight with a 6-3 7-6 (7-5) straight-sets win over Portugal's Joao Domingues.
Fellow Italian Lorenzo Sonego also made it through to the quarters by upsetting second seed Dusan Lajovic 7-6 (7-5) 7-6 (7-5).
David Goffin suffered a shock straight-sets defeat to Belarusian qualifier Egor Gerasimov in the second round of the Open 13 in Marseille.
Having gone a break up in the first set, the Belgian lost four games on the spin to leave himself chasing the match.
Goffin survived match point at 5-3 in the second set but was ultimately beaten 6-4 7-6 (7-5).
Top seed Daniil Medvedev came from behind to beat Jannik Sinner 1-6 6-1 6-2, while there were also wins for Felix Auger-Aliassime, Gilles Simon and Denis Shapovalov, who saw off former US Open champion Marin Cilic in three sets.
In Delray Beach, the favourites had little trouble as Milos Raonic and Ugo Humbert earned quarter-final spots with straight-sets victories over Cedrik-Marcel Stebe and Miomir Kecmanovic respectively.
They will be joined in the last eight by Americans Steve Johnson and Frances Tiafoe after they eliminated compatriots Jack Sock and Tommy Paul respectively.
Halep on course in Dubai
Top-seeded Simona Halep came from a set down for the second day in a row to beat Aryna Sabalenka 3-6 6-2 6-2 Thursday and reach the semi-finals at the Dubai Duty Free Tennis Championships.
Halep will next face Amerian qualifier Jennifer Brady, who upset former No 1 Garbine Muguruza 6-7 (5-7) 6-3 6-4 to reach her third career WTA semi-final.
Kazakhstan's Elena Rybakina produced another upset by beating second seed Karolina Pliskova 7-6 (7-1) 6-3. Rybakina, who leads the WTA Tour with over 100 aces this year, will face Petra Martic in the final four after the Croatian beat Anett Kontaveit 7-6 (7-4) 6-1.
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