The Light Blues got off to the perfect start in their second round tie at Mosset Park when Kal Naismith’s first senior goal for the club put them ahead.
But Gers failed to build on that and despite enjoying large period of possession, they couldn’t add to their tally.
Indeed, they had to rely on a couple of important saves by goalkeeper Alexander to ensure they hung on to their lead.
The 34-year-old was visibly irritated by the fact the Ibrox men were clinging on to their advantage rather than pulling away from their opponents.
And he has called for a dramatic improvement for Ally McCoist’s squad as it continues to struggle away from home.
Alexander said: “It was an extremely frustrating day. Once again, we’ve not played the way we have wanted to away from home.
“When we go 1-0 up, we expect to keep possession and to make the opposition run around a bit but it never happened today.
“As soon as we scored, we switched off and stopped doing what we had done to get the goal in the first place. We made life hard for ourselves.
“We need to kill teams off by scoring more goals than we are getting. We’re not being clinical enough.
“I don’t think we had more than two shots on target and if you don’t hit the target, you don’t score goals.
“It ended up being an uncomfortable afternoon for us and it shouldn’t have been. We should be beating teams at this level 4-0 or 5-0.
“Full credit to Forres. They came out, did well for themselves and in all honesty they maybe deserved a draw from the match and a replay.
“To be brutally honest, the only positive thing we can take out of the game is the fact we are in the next round and we’ll look forward to the draw.”