Rangers lost ground in the Scottish Premier League title race after being held at home by Aberdeen.
Nikica Jelavic had a header tipped onto the bar by Dons goalkeeper Jason Brown and Aberdeen's Kari Arnason came close at the other end.
Arnason broke the deadlock with an excellent strike in the 63rd minute.
Maurice Edu's deflected shot quickly restored parity, both goalscorers came close again and Brown denied Sone Aluko before the end.
With Celtic having beaten St Mirren earlier in the day, Rangers now trail the league leaders by four points.
Aberdeen opened stoutly, keeping their hosts largely at bay for the first 20 minutes.
Chances came Rangers' way when an Aluko corner was flicked on to Jelavic and his header was fisted onto the bar by Brown.
The keeper's work was not yet done as he made a reaction save as a scramble in the box ensued, ended by the referee's whistle to award a free-kick to Aberdeen.
Moments later, a flick-on by Jelavic sent David Healy through on goal, but the Northern Ireland striker slipped the ball wide with the goal at his mercy.
It was Aberdeen's turn to threaten and Fraser Fyvie's corner was met by the head of Arnason, the ball clipping the top of the crossbar on its way out.
Aluko flashed a shot wide from distance and Lee Wallace and Edu were also off target as Rangers pressed towards half-time.
A Steven Davis cross early in the second half missed Jelavic but found Wallace and his effort hit the post before the Dons eventually cleared.
Chris Clark's powerful shot needed dealt with by McGregor and, from the corner, the keeper missed the cross and required a goal-line clearance by Carlos Bocanegra as the home side claimed in vain for a handball by Arnason.
Rangers failed to heed the warning of Aberdeen's growing confidence and were punished after Davis lost possession near halfway.
Clark led the break, fed Arnason on the left and the midfielder beat McGregor with a sublime finish.
Aberdeen were immediately on the retreat as Rangers shelled balls into the box and the hosts' pressure eventually paid off when Edu's shot from the edge of the box was diverted past Brown by a Dons defender on 67 minutes.
Rangers continued to pour forward and the visitors were forced to defend a number of corners.
However, the Dons were almost in front again when Arnason tried his luck from 30 yards and McGregor got down low to make the save.
Jelavic did well to set up Edu, but the angle beat the midfielder as he ran in at the back post to shoot wide.
Continued pressure from Rangers failed to yield a second goal and Bocanegra was fortunate to escape with just a yellow card after taking down Josh Magennis as the Aberden forward ran through on goal in a late break.
Aluko forced Brown into a save with a 16-yard volley deep into injury time and, from the resulting corner, the keeper made another save to deny Bocanegra.