Cape Town - Orlando Pirates coach Vladimir Vermezovic admits some of his side's mistakes against Maritzburg United on Tuesday were "unacceptable" after the Soweto giants slumped to a 2-1 defeat.The Buccaneers found themselves trailing after just two minutes at the FNB Stadium as Mohammed Anas fired the Team of Choice ahead, and although Kermit Erasmus managed to draw the sides level soon after, Anas competed his brace before the break to eventually ensure the win.The result left Pirates sixth in the Premiership standings and 12 points behind leaders Kaizer Chiefs, who they take on in the Soweto Derby on Saturday, and Vermezovic knows his side simply cannot afford performances like that in midweek if they are to return to the top of the pile in South Africa.Speaking after the match, the Serbian tactician said: "It was a game of too many mistakes. I don't think I understand - for a team with such experience to concede goals in the second and 45th minutes... it's unacceptable for me."Vermezovic endured plenty of abuse from the Pirates supporters even before the game after dropping fan favourite Patrick Phungwayo for Thabo Matlaba, but the coach insists he had little choice in the matter, considering the former's contributions for Bafana Bafana in the Nelson Mandela Challenge on Sunday."Patrick played two days ago, 90 minutes for Bafana, and he wasn't ready for the game today. Thabo Matlaba didn't play for something like seven weeks, but he is in full training and is the natural substitution for Patrick," the coach concluded.