Ulster 13 Glasgow Warriors 25:Glasgow earned a valuable away win to move to the top of the Magners League table at a wind and rain swept Ravenhill.
Warriors outhalf Dan Parks kicked 20 points alongside Thom Evans' second-half try on a night when Ulster, who were missing injured trio Stephen Ferris, Paddy Wallace and BJ Botha, were punished for an error-ridden display.
All of Ulster's points came in the first half, with Tom Court scoring a try and Ian Humphreys kicking two penalties and a conversion as the visitors moved top of the table on points difference from Edinburgh.
The Warriors opened with a Parks penalty after five minutes and then, five minutes later, Thom Evans was put clear by Richie Vernon and was hauled down short by fellow Scotland international Simon Danielli.
The Warriors won a penalty from the resulting breakdown but Parks' effort stayed right as he kicked into the wind.
Humphreys was then on target with his first effort to tie the scores but he missed a second effort.
The Ulster fly-half made up for his miss with a well-struck effort to give Ulster a three-point lead which was stretched to 10 points when Court was driven through a seven man Glasgow pack following prop Jon Welsh's sin binning.
Humphreys added the extras but Parks hauled back three points for the Warriors with a long-range penalty in injury time to give Ulster a 13-6 lead at the break.
With the elements behind the Warriors, Parks kicked two penalties shortly after the resumption to tuck the visitors in behind Ulster by a solitary point.
Parks gave the visitors the lead after Ulster's hands strayed on the ball on the ground and after a sustained period of pressure from Ulster, the number 10 landed his sixth penalty to make it 18-13 to Glasgow.
He had another long-range chance to further their lead but was wide from 45 metres. Still, he made up for it with a great bomb which Humphreys missed and the ball was snaffled and driven on by John Barclay.
The Warriors forged forward to Ulster's line and replacement scrum-half Chris Cusiter dummied from the ruck, broke right and put Thom Evans in at the right corner.
Parks nailed a superb conversion and Glasgow to seal victory.
