Saints boss Nigel Adkins shuffled his side around in a bid to take the three points.
Shaw was one of those brought into the side, with the 17-year-old left-back becoming Southampton's youngest ever starter in the Premier League.
"I don't think it was a gamble at all because we believe in him," Adkins said.
"I think if he hadn't have been ill after the Stevenage game, he was knocking on the door then.
"We want competition for places and we've got a very young side. I don't know what the average age was but we believe in the youth system we've got here and we want to give them the opportunity to go and perform and play.
"Unfortunately he has come off with a bit of cramp there before the end, which is understandable I would imagine.
"I thought Danny Fox did ever so well when he came on so again competition for places is what you want."