Dominic Thiem was forced to work hard for his win over Andreas Haider-Maurer to reach the quarter-finals of the Generali Open on Wednesday.
The top seed fought back from a set down to defeat Haider-Maurer 1-6, 7-6 (8) 6-4 on the clay courts of the Austrian city of Kitzbühel.
The world number 21 was completely outplayed in the opening set, as his compatriot ran out to a 5-0 lead before Thiem finally held serve.
The second set was a tough affair, as both players managed to hold serve and eventually force a tiebreaker.
Thiem won the first three points and while Haider-Maurer saved two set points, Thiem would grind out the win to send the match into a decider.
The 2014 runner-up was then forced to come back from a break down to take the final set and the match.
"I'm happy to be in the quarters here," the 21-year-old told atpworldtour.com.
"Unfortunately I had to beat my countryman to make it to the next round. Andreas would have deserved to win this one. He played a great match. The atmosphere was very nice. The crowd was cheering for both of us."
Waiting for Theim in the quarters is Albert Montanes, who eased past Argentine Diego Schwartzman 6-1, 6-3.
In other results, third seed Fabio Fognini dispatched Dennis Novak 6-1, 6-2, while Paul-Henri Mathieu knocked out fourth seed Martin Kilzan 6-3, 7-5.