Mols broke the deadlock just before he was to be substituted
Rangers 2-0 Partick Thistle
Two goals in five minutes from Michael Mols finally broke Partick Thistle's stubborn resistance to stretch Rangers' lead at the top of the Scottish Premier League to nine points.
It looked like the advantage might be handed to Celtic in the title race as the home side struggled to make the breakthrough in the Glasgow derby at Ibrox.
Shota Arveladze was waiting on the touchline to replace Mols when the Dutchman broke the deadlock after 70 minutes then quickly followed it up with his second.
Until then, Thistle had produced the better chances and looked poised to claim the draw that would have given champions Celtic the chance to narrow the gap to four points with two games in hand when they face Dundee on Sunday.
Injury and suspension-hit Rangers missed the presence of banned inspirational skipper Barry Ferguson.
It was Michael who was coming off until he scored the goal
Rangers boss Alex McLeish
Partick were without Martin Hardie through suspension, but Jamie Mitchell proved a more than ample deputy as his lively footwork inspired his side's midfield.
Thistle boss John Lambie had to make another change to his line-up after only nine minutes, when Thistle lost the cool assurance of Scott Paterson at the centre of the defence to injury.
Former Scotland international Derek Whyte came on to make his long-awaited return from injury.
Thistle squandered an excellent chance to take the lead while waiting to make the substitution.
Mitchell sent Gerry Britton clear, but the striker delayed his shot long enough to allow Fernando Ricksen to block his effort at the edge of the box.
Stephen Hughes (left) was deputising for Barry Ferguson
Britton did force Stefan Klos into the action with a quick turn and shot from 16 yards that was well held by the goalkeeper.
Rangers eventually created a chance after 25 minutes, when Peter Lovenkrands' snap shot from 20 yards was blocked clear by goalkeeper Kenny Arthur.
Klos prevented Thistle taking a shock lead early after the break, when Alex Burns pounced on a poor back pass from Maurice Ross but had his effort blocked by the goalkeeper.
Rangers brought Neil McCann and Claudio Caniggia on for Maurice Ross and Mikel Arteta and started to apply more pressure - and create more chances.
It eventually produced a goal when Stephen Hughes did well to turn the ball into the box from the by-line and Mols met the midfielder's near-post cross to head the ball home.
Mols pounced again to drive low into the net after a Ronald De Boer pass fell into his path off defender Derek Fleming.
Thistle missed a chance to put Rangers under pressure, when substitute Ricky Waddell fired against the legs of Klos from only five yards out.
Rangers: Klos, Ricksen, Moore, Malcolm, Ross (McCann 50),
Arteta (Caniggia 61), Konterman, Hughes, De Boer, Mols,
Lovenkrands (Arveladze 76).
Subs Not Used: McGregor, Eggen.
Goals: Mols 70, 75.
Partick: Arthur, Lilley, Craigan, Paterson (Whyte 9),
Archibald, Mitchell, Buchan, Fleming (Waddell 78), Rowson,
Burns, Britton (Walker 85).
Subs Not Used: Pinkowski, Gibson.
Referee: K Clark