The loosehead prop, who made his international debut in 2012, feared his World Cup dream was over but he has made a swift recovery.
Now Grant, who helped the Warriors lift the GUINNESS PRO12 title last season, has his sights set on Scotland's opening clash with Japan on Wednesday.
"When it first happened I thought I was done," said Grant, recalling the Ireland game. "I thought I'd done something really bad.
"When you suffer that type of injury you get a buzzing feeling in your ankle that goes away after a while, and then you think you can stand up. So by the time the stretcher came over I said to the doctor that I was capable of walking off the pitch.
"The first 48 hours were pretty agonising. The ankle was badly swollen and I just hoped for the best. I was thinking the worst, but James [Robson, the team doctor] and his team were very positive.
"You know your own body and I'm fine now. It's a credit to the medical team, who have been great with me over these last three weeks.
"I've barely had a moment to myself, but they've got me back fit to start the World Cup and I'm nothing but grateful for that. I'm ready to face Japan."
And come what may during the competition, Grant is confident he will return to Scotstoun next month much improved.
"I'm definitely a better player for working in the camp," added the 29-year-old. "I can still remember coming into camp and working through a few drills Vern (Cotter) wanted us to do and the balls were going left, right and centre.
"Some of the sessions we went through were so hard, but if we did that now they would be some of the easier sessions. That's the level of skills we have now.
"The boys were being asked to do things which they wouldn't normally have been expected to do. Skill wise and fitness wise, all of the boys are a lot further forward."
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