Dominic Thiem fought from 5-2 down in the final set and held off a match point before upsetting the eighth-seeded Marcel Granollers 2-6, 6-3, 7-5 in the second round of the Hamburg Open on Tuesday.
The 55th-ranked Austrian saved five of the eight break points he faced and converted three of his 12 chances to defeat the Spaniard in 2-1/2 hours. Granollers, ranked 40 places above Thiem, was granted a first-round bye at the clay-court event.
Thiem is now 2-0 against Granollers after also beating the Spaniard in his native Barcelona in April.
Thiem next plays either Guillermo Garcia-Lopez of Spain or Leonardo Mayer of Argentina, who defeated German wild card Peter Gojowczyk 6-3, 6-2 in the first round.
In other first-round matches, 2012 champion Juan Monaco of Argentina defeated Pere Riba of Spain 6-3, 6-1 and Slovakia's Martin Klizan defeated Dutch player Igor Sijsling 6-4, 3-6, 6-0.
Klizan now faces 2011 winner Gilles Simon of France, while Monaco will play Andreas Seppi of Italy, with the winner taking on top-seeded David Ferrer in the third round. The Spaniard, who accepted a wild card to the tournament, rallied to defeat Mikhail Kukushkin of Kazakhstan 2-6, 6-3, 6-2.
Third-seeded Tommy Robredo of Spain, who won the tournament in 2006, beat compatriot Daniel Gimeno-Traver 6-2, 7-5 for a third-round clash with the 14th-seeded Joao Sousa of Portugal or Lukas Rosol.
Rosol reached the second round when German wild card Julian Reister had to withdraw with the Czech leading 6-4, 2-1.
Poland's Jerzy Janowicz defeated Spanish qualifier Albert Ramos-Vinolas 6-0, 7-5 for a second-round clash with the fourth-seeded Alexandr Dolgopolov of Ukraine. Also, German wild card Alexander Zverev eased past Dutchman Robin Haase 6-0, 6-2 to meet the fifth-seeded Mikhail Youzhny, also given a first-round bye.
Santiago Giraldo of Colombia advanced after defeating Benoit Paire of France 7-6 (6), 6-2 in their second-round match.
