SOUTHAMPTON is gearing up for a mass exodus as thousands of Saints fans prepare to travel to the club's biggest football match for years.

Up to 20,000 Southampton fans will descend on Birmingham on Sunday as Saints attempt to make their first FA Cup final for 27 years.

More than 110 coaches and scores more minibuses will leave the city to watch the club's crunch semi-final with Watford at Villa Park.

All of the 18,922 tickets given to Saints for sale to fans have long since been snapped up. Around 3,000 tickets for the semi-final allocated to other clubs around the country have also gone. With tickets for the sell-out match fetching up to £250 on the Internet West Midlands police have warned fans: ''If you haven't got a ticket, don't come.''

Thousands more fans are due to pack pubs and clubs across Hampshire to watch the match, which kicks off at 4.30pm.

Coaches will leave for the 135-mile journey from Saints' stadium in St Mary's from 9am on Sunday and stop at pick-up points in Eastleigh, Winchester and Newbury. The fans will be joined by thousands in private cars. Roadworks due to take place on the junction of the M42 and M40 near Birmingham on Sunday have been suspended.

Railway engineering works are taking place between Winchester and Woking on the Southampton-Waterloo route on Sunday. It means that fans travelling by train will take 25 minutes longer to complete their journey.

The track has been reduced to single-line operating between Winchester and Woking but South West Trains say the normal number of Sunday trains will be running on the line.

Virgin's direct line service to Birmingham is not operating on match day - due to engineering works. Supt Matthew Greening of Southampton police said: "There are contingency plans in place for any trouble but we aren't expecting it. It would be a terrible shame if anybody spoilt the big day."

A spokesman for West Midlands Police said: "We expect supporters of both clubs to come along to the match and enjoy a great game.

"We would warn anybody who might be intending to cause trouble we will not tolerate such behaviour and that they will be dealt with firmly.''