Mario said he will be dancing the foxtrot and the mambo Monday night on ABC's Dancing With the Stars -- and the foxtrot has him worried.

"It's tough, because I'm not really a fan of foxtrot," the 21-year singer said in his weekly Sun interview. "I feel like the mambo fits me a lot better -- it's a fun dance with a lot of movement, and it's really, really fast."

Mario says he likes all the Latin-themed dances he's done of the hit show -- tango, samba and paso doble.

"With the energy of the Latin dances, when you're moving, your body just kind of follows through with it. But with the more formal dances like the foxtrot, it's just hard for me. I guess it's because I'm tall and my arms and my legs are long -- it's just is harder for me and takes more practice."

But practice he will, the Baltimore-born performer says: "The foxtrot is very formal and slow, and I just don't like it.  But, hey, I have to do it, and I'm going to give it my all. I didn't come this far to give up."

(Photo courtesy of ABC)