The 29-year-old striker thinks that it would be difficult for him to play against the Reds in a serious game so is relieved to be meeting his old teammates in a non-hostile atmosphere in London.
The two clubs will face each other in the International Champions Cup game on Saturday.
"Wembley Stadium is special and I played three or four games there: the semi-final I scored against Everton; and then we won the Carling Cup on penalties; we lost the [FA Cup] final against Chelsea," he told Liverpoolfc.com.
"It's important for this game that it's a friendly game because if it was in the Champions League or a really good tournament, it'd be difficult to play against Liverpool. But a friendly game is to enjoy."