Aaron Wilbraham, who stepped in for Murray at The Amex, has told Zaha he can sign off his Eagles career by leaving the Hornets running scared at Wembley.
Wilbraham, who played in the Prem with Norwich, said: "Watford will be fearing him.
"I said to him 'everyone in the stadium from Watford will be fearing you, so don't disappoint them.'
"He has got pace to burn and so much skill. If he gambles more in the box like he did for his first against Brighton, he will score plenty of goals.
"He is still young. Kevin Phillips and I were talking to him after the game about gambling in the box.
"If he keeps doing that, he can score every week. He is learning still but he is an unbelievable player.
"If he plays like that in the final, he could be the key. We need our big players to turn up and Wilf is definitely that for us."