WHILE most of Scotland's top swimmers face a nerve-racking bid for Commonwealth Games selection at the British Grand Prix Finals in Sheffield today and tomorrow, triple Olympian Alison Sheppard is staying at home to chase a first world record.

The only Scot to have already been pre-selected for the games in Kuala Lumpur in September, the 25-year-old was in relaxed mood as she looked forward to making her Masters debut in the British Championships at Glasgow's Tollcross Leisure Centre.

''It's nice to be the youngster again,'' said the Milngavie girl. ''The world record in my age-group (25-29) is 26.68sec for the 50m free-style and that's what I'm going for.''

But for the Sheffield contingent, it will a far more pressurised couple of days, and Scotland's director of swimming Martyn Woodroffe, has already fired a warning to the list of games hopefuls.

''Recent performances suggest that achieving the minimum level four qualifying time might not be enough to make the team,'' he observed. ''We already have six who have made the grade, and I'm looking forward to some good times, and some great swimming this weekend.''

In addition to Sheppard - the only Scot with a level one time - the other five who have already achieved the minimum qualification are Bryan Morgan, Graeme Smith, Kirsty Thomson, Lynn McLaren and Beverly Robertson.

The nearest challengers include Teresa Davies, Michael Cole, Louise Coull, Paul Latimer, Alasdair Pullan, Richard Hope, Diana Borland and David Leith. They are all within touching distance.

This weekend is the penultimate chance: the final one to gain the selectors' nod comes at the Scottish National Open Championships at the Tollcross Centre in Glasgow from June 11 to 14.

For Warrender's Leith, whether it turns out to be a dream or a disappointing summer rests on his efforts over the next three weeks.

In addition to the Games, he is also hoping to gain selection for the British team for the European Junior championships.

The 18-year-old is within striking distance of the qualifying times in both the 100 and 200m free-style. Summing up the feeling of all the Scots, he said: ''I'm trying not to get too uptight, but I am quietly confident that I'll make it in Sheffield.

''It would be nice to get qualification out of the way before the Scottish championships. I'm not far away from the times I need to get to the Games, and the European junior standard is about the same.''

Last year, Leith was unlucky to miss out on a place in the British team for the European Junior championships staged in Glasgow. It has made him even more determined not to miss out again.

''I went through to Glasgow, but it was horrible being a spectator,'' he reflected.

''This year, it would be great to be in two teams, competing for Britain in the juniors and then for Scotland at the Commonwealth Games.''