Alex Rodriguez praised Jennifer Lopez's ''relentless dedication'' as she headlined Madison Square Garden on Friday night (12.07.19).

The former baseball star paid tribute to his fiancée as she performed in her hometown of New York, despite the ''long and arduous'' road.

He wrote on Instagram: ''Bronx to Madison Square Garden. For a cab driver, it's just a 9.2-mile ride. But for @jlo, the road from being a kid running around with holes in her shoes in the Bronx to headlining at the world's most famous arena, was long and arduous and took years of hard work and relentless dedication. Keep on killing it girl #ItsMyParty #boss (sic)''

Meanwhile, Alex heaped praise on Jennifer after she struggled with a string of toughs show in San Jose, California, and Las Vegas.

She tells him: ''It was a tough show for me.''

To which he replies: ''It was the best show I've seen so far. It was Saturday night in Vegas and you guys killed it. And you showed why you're a champion, baby. Every time I see the show it keeps getting better and better and better. But wait, I don't know what you're talking about! Your voice was the best I've ever heard it! Babe, when you held that note, are you kidding me? And your voice ... by the way, you've never sounded better.''

Alex recently branded Jennifer as a superhero.

He said: ''I've never met anyone who's more honest. She's so authentic and genuine. It was strange to see someone of such magnitude be so normal, be such a great mother and partner and friend. How can you be like this and then go perform in front of 80,000 people? But that's her superpower.''