St Mirren staged a second-half fightback to stave off a Petrofac Cup upset last night.

The Buddies, who have lost their first two Championship games, looked to be in trouble when they trailed League 2 side Annan at the break.

But goals after the break from Jordan Stewart and Alan Gow ensured the Paisley men marched into the third round and gained a much-needed boost ahead of Friday's Renfrewshire derby at Morton.

Buddies boss Ian Murray rotated his squad as he made seven changes to the side that lost 2-1 to Dumbarton on Saturday. Right-back Jason Naismith was one of those to drop out after learning yesterday morning that he will be out for six months with knee ligament damage.

Among those to come into the team were debut keeper Jamie Langfield, who joined last week.

Incredibly, the veteran stopper's first task was to pick the ball out of the net after Annan raced into a shock lead. With just 16 seconds on the clock, Jim Goodwin was judged to have fouled Josh Todd in the box and a penalty was awarded. Former Morton man Peter Weatherson made no mistake in firing the underdogs ahead from the spot.

St Mirren threatened an equaliser three minutes later, but Calum Gallagher's header from a Stevie Mallan free-kick was deflected inches past.

Cameron Howieson had a great chance to level for the Buds when he burst through the middle in the eighth minute, but his tame shot from inside the box was easily saved by Jordan Hart.

The visitors had a penalty claim waved away after Lewis McLear fell under a challenge from Annan skipper Steven Black.

At the other end, Weatherson tried his luck from 20 yards but was denied by Langfield.

Annan had an even better chance in the 15th minute when Stuart McColm latched on to a long ball over the top but with just the keeper to beat he blazed his shot high over.

The Galabank side were more than holding their own and almost doubled their lead in the 28th minute when Todd pinged a 25-yard shot towards the top corner but Langfield did superbly to claw it away for a corner.

Saints threatened in the 39th minute but Gow's strike from just outside the box was palmed away by Hart.

A minute later the keeper tipped over Gallagher's header from a Jordan Stewart cross. McLear then volleyed a 20-yarder inches past as the visitors cranked up the pressure before the break.

Annan started the second half on the front foot, with Todd and Rabin Omar both going close with long-range strikes.

But St Mirren levelled in the 51st minute when left-back Stewart arrived to rifle in a superb low shot after Barry Cuddihy's cross from the right was headed out to him on the edge of the box.

Langfield had to make a vital save to stop Weatherson bundling in a Martin McNiff cross from close range in the 59th minute.

And it was to prove a pivotal moment as St Mirren edged ahead seven minutes later when Gallagher cut the ball back for Gow to fire in a low angled shot from eight yards out.