Alex Rodriguez shakes a leg during fiancee Jennifer Lopez concert

While American singer-actor Jennifer Lopez performed live at the Philadelphia for 'Its My Party' concert tour, her fiancee Alex Rodriguez showed off some dance moves in the front row with his daughters.

According to US Weekly, Alex can be seen dancing with his daughters, Natasha, 14, and Ella, 11, and the singer's daughter, Emme, 11. A video taken at the concert on Saturday showed him jumping up and down as his bride-to-be sings her hit number "Dance Again."

The 43-year-old former New York Yankees star also showed his support for the 49-year-old singer in one of her recent YouTube uploads. In that video, Alex reassured the pop star after what she called a "tough" show.

"It was the best show I've seen so far," he said, complimenting his fiancee and her backup performers. "You guys killed it! And you showed why you're a champion, baby. You were down and you still came back up and had the best show."

He continued: "You don't see how great you are. You really have no idea. Baby, nobody's looking at steps. People are looking at how beautiful you look and how great you sound."

Lopez later babbled about the pep talk to her long-time manager, Benny Medina. "That's why I love him and I'm gonna marry him," she said of Alex. "Whether he wants to or not, we're getting married. We're getting married forever."

Rodriguez popped the question to Lopez with a $1.4 million, 15-carat classic emerald-cut diamond engagement ring during a Bahamas trip in February.

"Marriage is something that became important to both of them and their kids," a source told Us Weekly then. "They know they want to make this commitment to forever together.