LONDON, April 16: Chelsea set up a dream FA Cup final against Manchester United at the New Wembley on Sunday but needed an extra-time goal by Michael Ballack to beat a spirited Blackburn Rovers 2-1 in a pulsating Old Trafford semi-final.

Chelsea took a deserved first-half lead through Frank Lampard but Blackburn stormed back after the break to level through Jason Roberts before Germany midfielder Ballack drove in the winner in the 19th minute of extra time.

Chelsea were the last team to win the FA Cup at the old Wembley in 2000 and manager Jose Mourinho heads to the new stadium aiming for his first victory in the competition and still on course for an unprecedented quadruple.

Chelsea, who had already beaten Blackburn three times this season in the League and League Cup, settled quickly and took the lead in the 16th minute when Ballack sent Lampard through to clinically clip an angled effort past Brad Friedel.

Andriy Shevchenko wasted a chance to put the game out of Blackburn's reach at the start of the second half by comically missing his kick when Drogba presented him with an empty net.

Blackburn made him pay when Roberts scored his first goal for the club when he cleverly diverted a low Pedersen free-kick in the 64th minute.

Hughes' should have won the game in normal time but Pedersen headed wide from Bentley's cross and Cech made an impressive save to prevent a John Terry own goal.

Ballack eventually settled it and there was still time for Michael Essien to strike the bar with a superb long range shot.

On Saturday, Manchester United booked their place in the first FA Cup final at the rebuilt Wembley Stadium when they beat Watford 4-1 in an entertaining first semi-final at Villa Park.

Two goals from Wayne Rooney and one each for Cristiano Ronaldo and Kieran Richardson secured United's path into the final, the first at Wembley since 2000.

Rooney put United ahead with a well-taken shot after seven minutes before Hameur Bouazza equalised for Watford in the 26th with a hooked volley that deflected past Edwin van der Sar.

Ronaldo put United back in front two minutes later with a close-range shot before Rooney made it 3-1 after 66 minutes with another close effort and substitute Richardson rounded off a somewhat flattering scoreline in the 82nd, five minutes after coming on.

United, who will be appearing in a record 18th final, have won the competition a record 11 times.—Reuters