Speirs saw his side slump to a disappointing 3-1 semi-final defeat on Wednesday to leave Queen's on the verge of missing out on a shot at promotion to the Irn-Bru Second Division.
It could have been worse for the Mount Florida outfit as they turned in an uncharacteristic below-par showing and toiled against the Blues.
Sean Winter and Craig Malcolm had Keith Knox's side 2-0 up midway through the first half and while Tony Quinn was able to pull one back for the visitors just after the break, Winter netted again to put Stranraer in the driving seat ahead of their return clash at Hampden this weekend.
It leaves Queen's with an uphill task on their hands if they are to progress to the final against Albion Rovers or Elgin.
Speirs knows his side can ill -afford another horror show if they are to emerge victorious at the National Stadium tomorrow afternoon.
He said: "It was a very disappointing night for us on Wednesday. We had a decent start and created a couple of chances, but then for the next 20, 25 minutes we couldn't seem to do anything right.
"We started defending really poorly and lost some poor goals, which is not like us.
"We could have lost a few more and we were grateful that we didn't. Our goalkeeper was excellent and made some great saves to keep the score down.
"We changed a few things and managed to get a goal back after a couple of minutes, but we didn't kick on from that.
"It was a poor performance and Stranraer should have been out of sight with the chances they created, they played very well. The reality is they are not out of sight, though, and we still have a chance.
"We have played so poorly in the first leg and we are fortunate that we are only two goals behind going into the game."
The Spiders will head into tomorrow's clash as outsiders to progress to the final, but Speirs remains confident his side can overcome the odds and move a step closer to a place in the Second Division.
Queen's finished an impressive campaign second in the standings behind runaway league champions Alloa and Speirs hopes they can return to top form when Stranraer travel to Glasgow.
He said: "We know that we will have to play a lot better in the second leg and we know that we can play a lot better.
"We will stay focused on the positives. We have a good record at Hampden, we have scored plenty of goals there and we know we are capable of getting the result we require.
"We know it will be difficult, but we feel it is very much doable."