"Peter has a phenomenal record and he is such a threat," said McClaren.
"He took a lot of stick tonight and was unlucky with some of the decisions which went against him. But he is an opportunist and he took his opportunity very well - even if I didn't see it.
"I'd just finished my half-time team talk and stayed in the dressing room to think about the second half. It's worked in the past - and it worked again! It was a very good goal."