Usher impressed by Taylor Swift’s hip-hop swag

Taylor Swift may have outdone herself when her Speak Now tour passed through Atlanta earlier this month. Continuing with her tradition of inviting surprise special guests on stage, she brought hip-hoppers T.I. and Usher out to perform their respective hits, "Live Your Life" and "Yeah."

When Usher received a call from Swift, he interrupted a play date at the park with his boys, Usher V and Naviyd, to take up the offer from the country darling.

Usher on country music artist Taylor Swift: "She's crunk for real." (Photo by Cindy Ord/Getty …"It started off as a simple day in the park with the kids," Usher said in an exclusive interview with Yahoo! Music. "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.'"

[ Photos: Usher on stage ]

Usher said he had two hours to make the trek across Atlanta to the Philips Arena. But his oldest son, Usher V. wasn't disappointed about shortening the time at the park. He was excited when he saw the stage.

"My son [was] looking at the stage saying, 'Daddy, I want to go on stage.' I'm like, 'Son this is not Daddy's show. It's Taylor's show.'"

Usher said he was impressed with Swift's hip-hop demeanor. She offered a convincing baritone-fueled version of Ludacris's rap in the song.

"For real, you guys don't even understand. Taylor, yo, she's crunk for real," Usher explained. "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 on stage."

For more of Usher, tune in on October 15 at 7 p.m PT for "A Decade of Difference" concert. He'll be joining artists like Lady Gaga, Juanes, K'naan, Kenney Chesney, Bono and The Edge to celebrate the charitable works of President Bill Clinton. Watch it live, only on Yahoo!