Australian No.2 Matthew Ebden is into the second round of the Halle Open after beating Malek Jaziri in straight sets.
The South African-born 30-year-old was ruthless in the opening set against the Tunisian before taking a tight second set in a tiebreak to win 6-0 7-6 (7-2) on Tuesday in Germany's northwest.
Ebden next faces German Philipp Kohlschreiber, whose match against Marton Fucsovics was evenly poised when the Hungarian was forced to retire with Kohlschreiber 2-1 up in the deciding third set.
Kohlschreiber holds a 1-0 advantage over the West Australian, with their only previous meeting coming at the 2012 French Open.
Stefanos Tsitsipas produced a dominant display to dispatch fifth seed Frenchman Lucas Pouille.
The Greek teenager, who had a run of success on the clay in Barcelona and Estoril, remained in full control from the first serve en route to a 6-2 7-6 (7-3) win.
Russia's Karen Khachanov also advanced to the second round with a 7-6 (7-5) 6-3 result over Germany's Mischa Zverev.