Jennifer Lopez in Rio de Janeiro, Brazil. Credit: GADE/AKM-GSI

Jennifer Lopez has shown off her rock-hard abs on several occasions, but while vacationing in Rio de Janeiro, Brazil on Monday, she covered up her stomach while flaunting her breasts in a sexy one-piece.

Hitting the pool with her 25-year-old beau, Casper Smart, and her twins Max and Emme, 4, the 42-year-old superstar showed off her incredible sculpted shoulders and cleavage in the swimsuit's plunging neckline. She covered up her famous booty with a striped towel and rocked giant silver hoop earrings and oversized DITA Eyewear Bluebird sunglasses.

"Just landed in RIO!!!!! One of my fave cities in the world! ?#JLOVE?!RS can't wait to Dance Again with you!! ?#jloDanceAgainTour?," she greeted her Brazilian fans via Twitter on Sunday.

After soaking up the sun, she gushed about her day of R&R on Monday and posted, "Beautiful day in Rio with my coconuts @Trios22 @BEAUcasperSMART and my Mommy ?#familia? ?#greattimes? ?#happygirl?."

Though they've only been together since Fall 2011, Lopez's relationship with her backup dancer has already gotten serious.

"She's telling friends she wants to marry Casper," one insider told Us Weekly in May. "She's certain she wants to be with him forever."