IT'S SEMI-FINAL time in the 2008 NAB Cup with four teams left in this battle for the pre-season prize.

Tonight, St Kilda will take the cottonwool off Nick Riewoldt as it looks to overcome a Bombers team which has been one of the surprise packets of this year's pre-season competition.

Essendon has implemented a heavy rotation policy throughout the NAB Cup, and that continues this week as it brings back some experienced heads while resting the younger players. But the policy didn't stop them from accounting for the Lions and the Bulldogs in the earlier rounds.

The Saints were impressive in beating the premiers Geelong in Canberra last week, but will be without Fraser Gehrig who was injured in the victory. Now they have to deal with a Bombers team with plenty to prove.

The Crows have been arguably the most impressive of the final four so far, accounting for Collingwood in Dubai and then blitzing the Dockers at AAMI Stadium on the back of some Andrew McLeod brilliance.

Hawthorn was unimpressive against a green Swans team in round one, but put together an awe-inspiring first term last week, leading Carlton by 54 at quarter-time to set up victory. But it will have to better than one impressive term against an Adelaide team with its tail up.