The match started well for Spain's Almagro, who broke Petzschner's serve at the first time of asking to open up a 2-0 lead.
Petzschner responded by holding his remaining service games, but it wasn't enough to stop Almagro from taking the opening set 6-3.
However, the German's response to falling behind was positive. Both players were broken twice during the second set, which left the score at five games apiece. Petzschner then held for a 6-5 lead, before a poor service game from Almagro handed his opponent the set.
It looked as though the third set was heading for a tie-break with the scores level at 5-5. Petzschner ensured that it wouldn't go that far though, as he repeated his feat from the second set to win through 7-5.
Almagro battled back in the fourth, running out a 6-4 victor to force a deciding set.