Country music star Taylor Swift has left a lasting impression on rhythm-and-blues singer Usher, who said he was impressed with her hip-hop swagger.

Swift's Speak Now tour was in Atlanta this month, and she had T.I. and Usher as surprise special guests to perform.

It started off as a simple day in the park with the kids, Usher told Yahoo! Music about when he got the call from Swift while he was with his sons. We have minivan adventures. Taylor hits me, and says, 'Yo Ush, I'm in town. I'd really love if you could come out and do 'Yeah' with me.' I'm like, 'Well, we haven't had any rehearsals.' [She said], 'No, no. The band's got it. You just show up.'

Usher said he was impressed with Swift's hip-hop swagger.

For real, you guys don't even understand, Usher said in the interview. Taylor, yo, she's crunk for real. In Atlanta, she came out. She did her thing. I didn't know she and hip-hop swag like that. She came out and they enjoyed it. Then, the finale, my kids came onstage.

Watch Usher's interview with Yahoo! Music below.

Watch their performance below.