Marin Cilic overcame Florian Mayer 4-6, 6-0, 4-6, 6-3, 6-1 for Croatia to lead Germany 1-0 in their first-round Davis Cup tie on Friday.
In the deciding set, Cilic broke Mayer in the first game and twice more to beat Mayer for the first time in three matches.
Croatia captain Goran Prpic says after Cilic trailed after the third set, he "decided to take the ball early and go for it."
Croatia No. 2 Ivan Dodig played Germany No. 1 Philipp Kohlschreiber in the second singles.