It was Thunder center Kendrick Perkins' decision to defend Dallas uber forward Dirk Nowitzki with 2:17 left in Saturday night's 99-98 victory over the Mavericks at Chesapeake Energy Arena. Perkins instructed Serge Ibaka to guard center Ian Mahinmi so Perkins could take a crack at Nowitzki. OKC coach Scott Brooks confirmed Perkins and Ibaka often are allowed to decide who guards whom. "I know Serge was battling with him (Nowitzki) the whole game, so sometimes it helps to take some of the pressure off him," Perkins said. "I just tell Serge, 'I got him. You stay back and protect the rim.' "Serge did a good job on him, but at the time we needed Serge to do what he do best, and that's protect the paint, so I just figured I'd lock in and defend him (Nowitzki) right then.