Rangers 1 Celtic 2
Celtic striker John Hartson scored and also won a penalty as the UEFA Cup finalists kept alive their hopes of a third successive Scottish Premier League title with an away win at arch-rivals Rangers.
Celtic weathered an early storm at Ibrox before taking the lead on 29 minutes, when Lorenzo Amoruso brought down Hartson and Alan Thompson made no mistake from the penalty spot.
A superb flowing move from the visitors brought a second goal two minutes before the break. French winger Didier Agathe fired in a low cross from the right, Henrik Larsson helped it on with a cheeky backheel and Hartson finished with a low strike from eight metres.
Rangers pulled one back 11 minutes into the second half when Ronald de Boer headed home Arthur Numan's cross, but it was not enough to prevent their lead being cut to five points.
Rangers have 87 points from 34 games, with Celtic now on 82 having played one game less.