Oxford United boss Jim Smith says his players need to grab their opportunity to play at Wembley because for many of them it represents a once-in-a-lifetime experience.

The U's have two nail- biting semi-final legs against Exeter City to get through to reach Wembley for only the second time in the club's history.

And Smith says the chance will not come around too often for the Conference play-off finalists to run out at the Football Association's showpiece national stadium He said: "Wembley is a massive incentive for everyone.

"It's a fantastic opportunity, and a very rare opportunity to play at a brand new Wembley because I would imagine, after this year, it would go back to Leicester or Stoke, or wherever it may be.

"They're trying to make sure the gatemen know what they're doing, and we've got the opportunity to play there.

"It may be that they play (the Conference final) every year there, but I would think not."

However, the U's boss will be urging his players to have their minds focussed totally on the job in hand in the two clashes with Exeter, because thinking too far ahead can make you lose concentration.

"You look at Stevenage and Kidderminster and they've hardly won a game since they were going to Wembley (in the FA Trophy)," Smith said.

Oxford United virtually sold out of their 1,350 or so ticket allocation yesterday for Friday's first leg at St James' Park.

Tickets are also selling well for the second leg at the Kassam Stadium next Tuesday.

Season-ticket holders and those with a stub from the home game against Stafford had their chance until last night. Remaining tickets went on open sale today.

Smith believes Oxford's famously vocal support can play a big part in helping the team through to the final, and will probably have more influence in the two semi-final games that in the wide expanse of Wembley - if Oxford make it there.

"We do have a big support and they can be a big help at Exeter in the first leg and at our place in the second leg," he said.

"I think you'd hardly notice them at Wembley, it's such a big stadium. I remember when we were at Wembley with QPR, the Oxford fans were magnificent."