Unai Emery’s side came back from a 1-0 first leg defeat against Nottingham Forest to secure a place in the Europa League final.
Watkins, 30, scored the first of Villa’s four goals minutes after picking up a head injury, his fifth of their Europa League campaign.
Speaking to TNT Sports after the game, Watkins insisted he and his teammates won’t get too carried away with their celebrations.
"In the first leg, we were very passive,” he said.
“They deserved the win, but it was always going to be more difficult at Villa Park. After the performance against Tottenham, everyone’s mind was on this game."
On Unai Emery's European record: "There’s no better manager than this to get us prepared for this game and take us into the final. His track record speaks for itself.
"We need to go and win it now."