Wayne Rooney scored twice and dished out an assist to help Manchester United thrash Watford 4-1 at Villa Park and book their place in the FA Cup final. English international Rooney fired United in front early in the first-half but Hameur Bouazza leveled the score in the 26th minute. Portuguese winger Cristiano Ronaldo restored the lead shortly after before two second-half goals from Rooney and Kieran Richardson wrapped up the win for United The Red Devils will face the winners of Chelsea-Blackburn tie in the FA Cup final at the new Wembley Stadium. Rooney needed just six minutes to break the deadlock when he collected Micheal Carrick's through pass and cut inside before unleashing a powerful drive past Watford keeper Richard Lee. Bouazza grabbed the equalizer in the 26th minute with an overhead kick that took a deflection off Gabriel Heinze and went into the back of the net. In-form Ronaldo put United ahead again two minutes later when he connected with Rooney's low cross to poke home from close range. United defender Rio Ferdinand had to be replaced six minutes before the interval due to a groin injury. Scottish midfielder Darren Fletcher was introduced. Rooney added the third six minutes past the hour mark with a simple finish after being set-up by Alan Smith before Richardson completed the rout eight minutes from time with a delicate chip.