ZAGREB, Croatia (AP)—Germany was a step closer to the quarterfinals of the Davis Cup after beating Croatia in the doubles for a 2-1 lead in their first-round tie on Saturday.

Christopher Kas and Philipp Petzschner outlasted Ivan Dodig and Ivo Karlovic for a marathon 6-3, 3-6, 5-7, 6-3, 6-4 victory.

During the match, Karlovic blasted a 251 kph (156 mph) serve, which was believed to be one of the fastest in professional tennis.

Playing for the first time together in the Davis Cup, Kas and Petzschner broke Karlovic’s serve at 4-4 in the fifth set. Only a game earlier, Croatia missed its opportunity at 0-30 at Kas’ serve.

“In the end, we were a bit luckier,” Petzschner said. “We did’t give up after being 1-2 sets down and I finally found the way to read Karlovic’s serve.”

Karlovic said: “Petzschner hit some great returns on my serve as no one ever did.”

In the opening singles on Friday, Marin Cilic overcame Florian Mayer 4-6, 6-0, 4-6, 6-3, 6-1, and Philipp Kohlschreiber saved a match point before beating Dodig 6-4, 3-6, 4-6, 7-6 (6), 6-4.

Reverse singles are scheduled on Sunday.