Martin Klizan became the first player to make it through to the quarter-finals of the Sofia Open by producing a final-set fightback to beat Lukas Rosol on Wednesday.
Klizan eased past Alexander Lazov in the first round of the inaugural ATP World Tour event in the Bulgarian capital, but the seventh seed had to roll up his sleeves to see off Rosol 6-3 2-6 7-6 (7-4).
Rosol, beaten by Stan Wawrinka in the third round of the Australian Open, led 5-2 in the final set, but failed to make it through to the last eight.
Klizan seized control of the match by winning the first three games at the Arena Armeec Sofia and saved a break point in what proved to be the final game of the first set, but Rosol hit back in the second to force a decider.
Rosol was on the brink of victory when he held to lead 5-2 after breaking in the previous game, but Klizan refused to be beaten and broke back to force a tie-break - which he won after claiming two mini-breaks to lead 5-1 and duly served out the match.
In the only other second-round match third seed Guillermo Garcia-Lopez made short work of qualifier Mirza Basic, easing a 6-3 6-4 success.
Daniel Brands' reward for a 7-6 (7-5) 6-3 victory over fellow qualifier Thomas Fabbiano is a round-two encounter with second seed Viktor Troicki.
Eighth seed Adrian Mannarino and Ricardas Berankis advanced to the second round at the expense of Evgeny Donskoy and Dimitar Kuzmanov respectively.