BOHEMIANS and St Patrick's Athletic in the Cup. Tonight at 7.45. The Gypsies and the Supersaints. A place in the FAI Harp Lager Cup final and local pride - fuelled by rivalries, some decades old, some new born at stake. A huge Easter crowd and the return of the Dalymount roar. They'll push themselves to the limit before they lose this one.

What's seldom is wonderful: a theory which, in the case of Bohemians St Patrick's cup ties, receives its first test in 16 years at Dalymount Park tonight. Remarkably, it is only the fifth time the clubs have been paired in the FAI Cup and, just as surprisingly, Bohemians have yet to beat their Dublin neighbours.

St Patrick's won a semi final in 1980, 1-0, courtesy of a Joey Malone goal, but even Jackie Jameson's magic couldn't see off Waterford in the final. Before then, St Patrick's won a quarter final replay, 1-0, at home in 1977 and emerged 3-1 and 2-1 from ties in 69 and 65.

If the truth be told, league meetings between Bohemians and St Patrick's in recent years couldn't have been seldom enough. Seven successive draws over three years, each one fading more rapidly from the memory. All has changed this season.

If tonight's semi final reproduces anything of last October's combustible premier division encounter at the same venue (St Patrick's won a hariy chested affair 1-0), then a huge crowd will be kept warm. The glow will be all the warmer if it emulates the three all thriller at Richmond Park in January, a game studded by more quality goals than some venues see in a month of Sundays.

Of course, this is a semi final and, all over the world, they are often anti climaxes. Both sets of players will be conscious of the possibility that one error could see their Cup run end. With each passing minute that consideration will intensify.

An early breakthrough would free the shackles. There are enough players on view to provide the decisive touches. Bohemians have the gifted, albeit moody, Brian Mooney, midfield driving force Tony O'Connor, rejuvenated goal poacher Derek Swan, and that superb footballer with plenty of football left in him, Peter Hanrahan. For St Patrick's there is the sublimely talented, big stage performer Paul Osam, the peerless Eddie Gormley, the wily Liam Buckley, the gifted tyro Brian Morrisroe, and the beloved Richmond Park cult hero Ricky O'Flaherty.

Discipline will be an important factor. St Patrick's had David Campbell sent off in the Dalymount game, but boast the better disciplinary record this season. Bohemians have the more combustible performers, most notably Donal Broughan. Referee Brendan Shorte has a big game ahead of him, too.

Overall, the pluses outweigh the minuses. These are the two highest scoring teams in the country, with 95 league goals between them in 56 games. Bohemians manager Turlough O'Connor vows encouragingly: "There'll be no change by Bohemians in that this has been a positive season and we try and win our matches. That has been reflected in the number of goals we've scored.

"There is an awful lot at stake," concedes O'Connor. "This is a Cup final amongst ourselves. It's a one off between two close Dublin rivals. But it could be a cracker and, like I've said, we won't change our approach."

St Patrick's have experienced three semi final defeats in their nine Cup runs under Brian Kerr. "Losing to Dundalk (four years ago) was probably my worst day in management, admits the St Patrick's manager. "I felt we did everything right, prepared well and played well, against a very good Dundalk team. But this is probably the best team, and the best squad, we've taken to a semifinal in my time here."

Another semi final defeat and Kerr's Cup crusade could become almost Clough like. His and St Patrick's time will surely come, but they nuts don't come any tougher to crack than Bohemians at Dalymount. It should be quite a night.