Serbia's world number 58 Filip Krajinovic reached the second round of the Hamburg European Open in Germany on Thursday, following a two-and-a-half-hour battle with Martin Klizan of Slovakia. A match that was played in searing heat swung wildly back and forth and only went Krajinovic's way in the deciding set. His 6-7(6), 7-5, 6-1 success set up a last 16 encounter with either Federico Delbonis of Argentina or number two seed and home favourite Alexander Zverev.