JOHN BARNES has experienced both sides of the coin in semi-finals with Watford at Villa Park - and says belief is the key to Watford pulling off victory against the odds tomorrow (Saturday).

The former England international was part of the side who defeated Plymouth in the last four to reach the Final in 1984. Barnes suffered the flip side three years later against Tottenham Hotspur and says it is not a pleasant experience.

"I've been a semi-final loser on two or three occasions and it's not nice," he said. "It's heartbreaking. The final is where you want to be, although I've lost there a few times as well."

Barnes has actually been a runner-up four times (1984, 1988, 1996 and 1998) but having reached the final on five occasions, is clearly an expert at negotiating the semi-final stage. His first experience came in 1984 against the Pilgrims.

"We were a top First Division club at the time, Plymouth were in the second division and we thought it was going to be a walkover," he recalled. "It wasn't - it was a very, very difficult match. The semi-final was a blur, I remember more about the final.

"The feeling after the Plymouth game was more one of relief than joy," he said of the 1-0 win. "It was such a hard contest.

"I remember it being a great two months until the end of the season because we were in about ninth or tenth place and didn't have the pressure of relegation or the pressure of qualifying for Europe."

Three years later, Barnes was back at the home of Aston Villa with Watford for another semi-final, this time against a much-fancied Spurs side.

It is not an afternoon Barnes - or Watford fans for that matter - have fond memories of. Minus injured keepers Tony Coton and Steve Sherwood, Graham Taylor played Gary Plumley in goal and saw his side dead and buried by half-time as Spurs hit four goals in 45 minutes.

"Once we lost our two goalkeepers the confidence and the belief just went," he said. "The four goals conceded were nothing really to do with Gary Plumley. We just weren't at the races."

Barnes agreed that Watford are even bigger underdogs tomorrow than they were against David Pleat side's that day.

"Watford are playing against the top team in the country this time and they are bang in form after they demolished Roma," he said.

"They are the underdogs but in a one-off occasion, anything can happen - look at Portsmouth beating Manchester United and then Watford beat Portsmouth. On that basis it should be a win for Watford!

"If players have the belief, the organisation and the concentration then anything is possible. Manchester United are favourites but they won't be taking this game lightly. They have been on the receiving end of enough upsets to know that.

"Sir Alex Ferguson is too experienced to know if they take it lightly and are complacent then they could come unstuck."