Well suffered a League Cup exit at the hands of Aberdeen on Wednesday but bounced back with three points.
The home side then lost Shaun Hutchinson to a straight red card three minutes from the end after he tugged down Heffernan as the striker ran through on goal, but they held firm under pressure to collect the win.
"I felt so low after the Aberdeen game and it was a combination of things," McCall said.
"Aberdeen have now knocked us out of the cup three times in a row and every team knew it's not often you can get into a semi-final that doesn't involve the Old Firm. The teams now in the semi-final won't have a better chance of winning a trophy.
"So to win is a massive relief because it has been a tough week.
"We were hanging on at the end, there's no doubt about that, but it was a gutsy display. It was a deserved three points if you look at the chances over the piece and it is a massive relief."
- Sports & Recreation
- Paul Heffernan