Thistle took the lead in 17 minutes when Joe Cardle slipped a great ball through to Aidan Fitzpatrick who showed great composure as he fired a left-foot shot into the right corner
And when they went two up six minutes into the second half everyone assumed they were home and dry. The excellent Cardle reacted quickest when James Penrice’s cross was cut out and placed a right foot shot into the right corner to claim his first Thistle goal.
However, nothing is simple at Firhill these days and Stranraer got a goal back barely a minute later when PJ Crossan slammed home a right foot shot from the edge of the box, set up by Mark Lamont,
It was panic stations as Conor Hazard had to make a vital save to deny David Brownlie and then Crossan’s shot was deflected a foot wide.
However, the nerves were soothed in 74 minutes when Gary Harkins played a clever free kick wide to Stuart Bannigan who clipped the ball to the back post where Steven Saunders headed home.
Then Blair Spittal added gloss when he slid in to convert Christie Elliott’s cutback nine minutes from time.
Caldwell said: “It’s never easy when you are playing lower league opposition but I thought we were excellent.
“They scored a good goal and had a decent spell for 10 minutes.
“Our intensity from minute one was very good and our energy levels in the last 20 minutes told in the end.”