Jennifer Lopez showed off her toned tummy in a black sports bra and matching pants by “Under Armour” on the set of a new music video on in Acapulco, Mexico. In other shots the “American Idol” judge was seen wearing tight-fitting leather pants and ankle boots while busting a move in front of the camera. “2nd Video in Mexico with @wisinyyandel #FollowTheLeader Love it here! #LosLideres Siempre al frente!” Jennifer tweeted the day before. J.Lo was joined by her beau Casper Smart. The lovebirds were seen getting affectionate in between takes.