Monteith and the singer met up recently at a group-bowling outing in L.A., and he says she "kicked my ass."
"I'm not gonna deny this. I was just an uncoordinated mess that day and I couldn't put the ball into the pins. I couldn't do it. It was bad," Monteith tells CMT Radio Live's Cody Alan. "She just brought the A-game. And I brought the B-game."
Despite the alley-whoopin', Monteith calls Swift "a great friend of mine," and when prodded on whether he thinks the singer is a "10," he laughed and said simply, "She's pretty fantastic."
The full interview with Monteith will air April 21 on CMT Radio Live with Cody Alan, which broadcasts weeknights from 7:00 p.m. - 12:00 a.m. ET.