High school musical 3 song help please!!!?

so in the movie hsm 3, art the end they do the final lk play (senior year) and at the beggining its kelsey and ryan singing and on the piano, and then that song goes into 'now or never' with them playing basketball.... what song is that called on itunes?? because the actual 'now or never' song doesn't have that same beg. of ryan and kelsey! where can i find it?? thanks so much!!!