The 27-year-old all-rounder has been a mainstay in the Bears middle-order this year, but he saw an opportunity to take an opening spot for the Metro Bank One Day Cup.
Having scored runs against a Warwickshire League XI on Tuesday, the right-hander proved it was the right decision firing a career-best List A score of 94 which guided Warwickshire to a four-wicket victory.
"It came from a conversation we had a few weeks ago," said Barnard. "I noticed we'd be short of a few batters and I chucked my name in the hat. I said to Robbo I'd like to give it a go and he said yes.
"My goal was just to stay in there really as I've had a few starts and haven't really gone on to that big score. To be there at the end, or near to it, and help us to a comfortable win was the pleasing thing."
Speaking of the competition, Barnard added: "We were told this week there's going to be a beer and cider festival and I always enjoy playing here. It's a great place to play cricket and the crowd really get involved. I know they're passionate about Somerset, but there were a few Bears fans too.
"We want to go out and win and we've got the squad to do that. Everyone's enjoying it."