Paul Scholes had opened the scoring for Manchester United after 58 minutes, but three minutes later Thompson equalised with a well-taken header.

And Rovers will now take the slender advantage of an away goal into the second leg at Ewood Park.

Manchester United created most of the game's modest tally of clear-cut openings but Ruud van Nistelrooy in particular was wasteful in front of goal, failing to convert two excellent chances.

And 17-year-old Blackburn defender James McEveley made a brilliant injury-time clearance off the line to deny Ole Gunnar Solskjaer and preserve his team's advantage.

Rovers - looking to reach their second successive Worthington Cup final - looked comfortable throughout the match and can go into the second leg confident of a positive result.

United settled quickly and seemed the most likely to score in the opening stages.

Crisp passing from Juan Sebastian Veron, David Beckham and Scholes created a series of half-chances and United's Argentine twice went close with long-range efforts.

Blackburn forced the first meaningful save of the evening with Fabien Barthez diving to his left to save a firmly struck drive from Lucas Neill after 30 minutes.

United should have opened the scoring seconds before the interval.

Scholes put Van Nistelrooy through on goal but the Dutch striker's poor shot from eight yards was saved by Brad Friedel.

And Van Nistelrooy missed an even better chance after 55 minutes.

David Beckham shrugged off McEveley down the right and played a low cross into Van Nistelrooy's path only for the striker to loop the ball over the Blackburn net from five yards.

United did take the lead, though, shortly afterwards.

A well orchestrated build up culminated with a first-time cross that Neill failed to clear and Scholes converted from two yards after his initial effort rebounded off Friedel.

But minutes later Rovers, who looked to be positive throughout the match, equalised.

Substitute Keith Gillespie crossed for Thompson to head into the bottom corner from eight yards.

Sir Alex Ferguson introduced Solskjaer and Diego Forlan as his team went in search of a first-leg advantage.

But his team's best opportunities fell to defenders, with Rio Ferdinand missing the ball, Mikael Silvestre blazing over and Gary Neville forcing a good save from Friedel.

And Rovers had their chances too - Dwight Yorke might have snatched a winner and Neill ended up booked for diving when replays suggested he had a reasonable penalty claim.

As the game moved into injury time United might have snatched the win Ferguson wanted, but McEveley brilliantly chested Solskjaer's shot off the line.

Man Utd: Barthez, Gary Neville, Ferdinand, Brown, Silvestre, Beckham, Veron, Phil Neville (Forlan 82), Giggs (Solskjaer 74), Scholes, van Nistelrooy.
Subs Not Used: Ricardo, Blanc, O'Shea.

Booked: Phil Neville.

Blackburn: Friedel, Neill, Taylor, Todd, McEveley, Thompson (Jansen 66), Tugay, Flitcroft, Dunn (Gillespie 19), Cole, Yorke.
Subs Not Used: Kelly, Ostenstad, Johansson.

Booked: McEveley, Neill.

Attendance: 62,740