Sixth seed Martin Klizan edged into the second round of the Moselle Open in Metz after home favourite Paul-Henri Mathieu retired due to injury.
Mathieu clinched the first set on a tie-break but trailed 6-7 (1/7) 6-3 3-2 when he was forced to pull out with an apparent Achilles tendon problem.
French seventh seed Adrian Mannarino overcame compatriot and qualifier Vincent Millot 6-2 7-5 to make straightforward progress to the next round.
And Fernando Verdasco was the third successful seed on Tuesday but the Spaniard had to work hard to overcome Germany's Alexander Zverev 6-7 (2/7) 6-3 6-3.
Canadian Vasek Pospisil beat Aleksandr Nedovyesov of Kazakhstan 6-1 7-5 while there also wins for Frenchman Edouard Roger-Vasselin and Germany's Mischa Zverev.
Source: PA