Grant, on duty in Liechtenstein for Northern Ireland midweek, is the worst casualty of West Ham players' international endeavours after coming off worst in a block tackle, and he says: "It is just one of those things. The ball was short, I was off balance, and he came through me - but it should be okay.
"I think it's a medial ligament; it is a bit sore and I have to go and get a scan when I go back to West Ham tomorrow - the doctor doesn't know himself how long it will be."
Glenn Roeder handed Grant his West Ham debut on the last day of last season when he was caretaker manager following the resignation of Harry Redknapp, and offered him a new contract at the club.
And he was hoping to get further first team experience this campaign once Premiership safety has been secured.
"Especially after making my full debut for Northern Ireland I was hoping to get a chance," he says, "but now we will just have to see how it goes. I was over the moon to get my first start for my country, though."
It wasn't the best of nights for club and country team mate Steve Lomas either - he was shown a red card early in the second half for an alleged elbow offence, and Grant adds: "Lomy has got sent off but he should never have been. He is a bit down about it because he knew their bench were jumping up and down saying he should go, and I think it was that that did it.
"He was raging about it and everybody was unhappy, but he can put it behind him and get on with it Saturday anyway."
The game finished goalless, but Grant insists: "We were down to 10 men in the 48th minute and if it had stayed at 11 men, which is nothing against Lomy who should never have gone, we would have won the game.
"It's just one of those things."