From mj's tour review:

Mandisa and Ace performed "I'm Your Angel". I wouldn't necessarily think of putting those two together, but they complimented each other nicely. They both seem like sweet souls and on the same wavelength when they perform.
Their vocal styles are very different, but it worked.

Ace:

"Father Figure"
"Harder to Breathe"

Ok. Uhhm. I think I've developed a little crush on Ace Young. Ahem. Shut up lolly. I'll leave it at that.

Ace's mannerisms can be goofy and cornball, but he's so sincere. Ace running his finger down his cheek as he sings the word "tear" should make me snicker, but it doesn't. Well, ok, maybe I'm snickering a little, but I can't help but smile.
I really enjoyed his set--his singing was much better live than it was on the show. "Father Figure" is one of my favorite cuts off the Encore CD.