Heading into the last few minutes of the match in Parma in Italy the Scots were 18-13 down and their hopes of going to the showpiece event in New Zealand next year looked all but gone.
However, Ireland had a player in the sin-bin and Scotland kept their composure to bag a try in the dying seconds through full-back Chloe Rollie and then replacement stand-off Sarah Law’s conversion gave them a famous 20-18 triumph.
It means that Scotland finished second in the European qualifying event behind Italy and will now go into a repechage tournament to play for the one remaining World Cup place.
“I 100 percent always believed that this would be the outcome because our players never give up,” back-row Malcolm said.
“We knew it might be in the last second - which is exactly what happened - but I am so proud of the fight and all the courage the girls showed on the pitch and I thoroughly believe we deserved that win.
“The heart, the passion, the work that has been put in by every one of the players in the wider squad over the last few months meant we believed we could do that.
“The way that the girls worked through the phases and kept their cool at the end also means that we can look forward to the future with confidence.”
Meanwhile, head coach Bryan Easson admits that Law is the “calmest member of the squad” and he never doubted she would make the crucial kick at the end.
“Sarah has such a good rugby brain and knows the game inside out, but for her to put down that ball and stay cool in such a situation and I never doubted that she could make it,” he explains.
“She has worked hard on her kicking with, amongst others, Chris Paterson and all that practice was for moments like this one.”