Christian Dailly was the unlikely scorer of Rangers' opening goal but Porter snatched a point for Motherwell with a second-half equaliser.

Rangers still have games against St Mirren and Aberdeen but Celtic's superior goal difference tilts the championship race in their favour ahead of their final game against Dundee United.

Rangers, three points behind Celtic, now have just one game in hand and a minute of applause was observed in memory of Celtic legend Tommy Burns, who lost his battle with cancer on Thursday.

A long ball from Kirk Broadfoot was met by Dailly and he was able to direct a header into the back of the net after the goalkeeper made the wrong call to come off his line.

Nacho Novo then had the ball in the back of the net again but the assistant referee had already flagged for offside.

Motherwell could have restored parity shortly before the interval but Neil Alexander did well to tip a well-struck drive from Brian McLean just over and Rangers headed into the break with the advantage.

Rangers should have extended their lead within a minute of the restart when Daniel Cousin pounced on a long clearance and a blunder from Stephen Craigan allowed him through on goal but Graeme Smith pulled off a decent save to deny the point-blank shot.

Instead, it was Motherwell who had the net bulging with 50 minutes gone. David Clarkson's header rattled off the post before the ball broke to Darren Smith, whose flick was turned in by Porter from close range.