Having finally won at home in the league last week, they now face Penicuik in the Scottish Cup next week and three wins in a row will surely breed confidence.
McCall said: “I thought we were sloppy for 15 or 20 minutes at the start of the second half. But Gary Harkins scoring right after they equalised took a lot of energy out of them.
“None of the games are ever easy. We have Penicuik next week and then two league games after that. Hopefully we can build some momentum.
“I think we got a lot from the Morton game last week. Not in a football sense but in a grit and determination sense.
“Penicuik will bring about 1500 supporters so it should be a good atmosphere.”
Stenhousemuir had their goalkeeper to thank for not conceding early as Graeme Smith made two terrific saves in the space of a minute.
The former Motherwell stopper brilliantly pushed Lewis Mansell’s header over the bar in 13 minutes after James Penrice had crossed from the left. Then Smith made a fine block on Penrice’s stinging left-foot shot 60 seconds later.
The Thistle full-back was the supplier again in 17 minutes when his deep cross seemed perfect for Joe Cardle but the winger made a complete mess of an attempted volley. It was no surprise Penrice was involved as Partick finally made the breakthrough four minutes later.
He slid a great ball down the left for Craig Slater who played a pass inside and Reece Cole slammed a right-foot shot that flew past Smith into the right corner of the net. Thistle, however, made life difficult for themselves by not really kicking on and the Warriors grew in confidence.
They found an equaliser in 68 minutes when Partick did not deal with Alan Cook’s cross into the box, the ball broke to David Hopkirk and he expertly fired a left-foot shot into the left corner.
The Stenny celebrations were short-lived as Thistle regained the lead less than two minutes later.
Cole’s corner from the left dropped nicely for Harkins, who shot home from barely two yards out. Craig Slater sealed the semi-final place 11 minutes from time when Cardle teed him up and he clinically shot past Smith.
Then Kenny Miller – who scored ten goals in 13 games in a loan spell with Stenny 20 years ago – added some gloss to the victory four minutes from time.
He took a pass from Cardle and brilliantly slammed a right-foot shot into the top right corner.
Stenhousemuir manager Davie Irons said: “When we got back level I thought they looked a wee bit shaky but to lose a goal soon after that was criminal.
“You talk about key moments in games and the second goal just took the steam right out of us and left us a mountain to climb.”