Ulster fell to a bruising 27-9 RaboDirect PRO12 loss to Glasgow in Scotstoun, a result that leaves them just a point above the Scottish side and which may put their hunt for a home semi-final spot in danger.
The visitors had moved into a 9-3 lead at one point in the first half thanks for the boot of Paddy Jackson, who was left to rue two missed kicks when Sean Maitland burst through the Ulster defence to touch down and add five points to Finn Russell's opening penalty.
Ulster appeared to have taken hold of the game with three penalties by Paddy Jackson in the middle of the first half but he had an important miss in the 31st minute and Glasgow closed the half with a fine try from Sean Maitland.
The conversion by Finn Russell added to his earlier penalty allowing Glasgow to go in leading 10-9 and they dominated the second half, scoring tries through Tommy Seymour and man of the match Mark Bennett, with Russell converting both and adding a penalty.
Glasgow can now look forward to an exciting end to the regular season as they seek a top-two finish, with a previously-postponed home game against Edinburgh next Saturday followed by Treviso away and Zebre back at Scotstoun.
The pressure is now on Ulster to retain a top-two place to ensure they get a home tie in the play-offs. They have the difficult all-Irish run-in of Leinster at home and Munster away to wrap up the regular season.
On a beautiful Glasgow spring evening the first scoring chance fell to Jackson but he sliced his effort from a central position on the home 10-metre line.
Glasgow looked the more likely at this stage with good work from Maitland and Seymour.
In the ninth minute full-back Peter Murchie broke to the Ulster ’22, won a penalty which was tapped and when interfered with, the advanced penalty was hit home by Russell.
Ulster were sloppy but as the first quarter ended they got their act together.
The Glasgow defence was put under pressure and three close-in penalties were conceded, struck home by Jackson in the 21st, 25th and 28th minutes.
The second of those saw Glasgow number eight Ryan Wilson pick up Glasgow's 10th yellow card of the season, sent to the sin bin by referee John Lacey.
Jackson missed a tricky penalty in the 31st minute and Glasgow hit back in the closing minutes of the half to go in ahead.
A break initiated by centre Mark Bennett was halted two metres out thanks to a brilliant tackle on Peter Horne by Luke Marshall.
But Glasgow kep the pressure on and a wonderful pass from youngster Russell put in Maitland for a 40th-minute try converted by Russell.
Within 10 minutes of the restart Glasgow led 20-9.
First Russell kicked a penalty, with Ulster flanker Sean Doyle sin-binned.
Then a Glasgow line-out drive, with backs attached, ended with one-time Ulster winger Seymour getting the touchdown and Russell converting from the touchline.
Ulster came back and Andrew Trimble was cut down under the Glasgow bar before a line-out drive was referred to the television adjudicator, only to be disallowed.
Glasgow, boosted by their defensive effort, got upfield and following a line-out drive, centre Bennett came back against the grain to reach the Irish line.
Again the TV official was given work to do and this time, in controversial circumstances, he awarded the try, which Russell converted.
Glasgow closed out the game in the Ulster half, with only a fine tackle from Trimble preventing them from getting the try bonus point.