Jennifer Lopez claimed she'd dump Alex Rodriguez if he beat her in a race.

The 48-year-old singer-and-actress admitted she's very competitive in all aspects of her life and she's constantly setting down challenges for his former baseball star boyfriend - but she's thankful he never seriously tries to take her on.

She admitted: ''I'm so competitive [in] every way. I don't know, something inside me, I'm competitive. When we work out I think, 'I can beat you.'

''We never challenge each other side-by-side. Like, if we go to UCLA, and we're doing the stairs or something, in my mind, I'm like, 'I'm killing it.'

''Here's the thing, he just doesn't even entertain my delusions. Like, I'll say, 'Babe, I feel like I could beat you.' And he's like [straight-faced].''

Talk show host Jimmy Kimmel said he thought Alex, 42, was making the right move in ignoring her attempts at competition, which his guest agreed with.

Jennifer quipped: ''There's no winning that because if he beats me, it's over!''

Since retiring from his playing career, Alex has carved out a successful career commentating on baseball games and the 'Dinero' singer loves attending the games he's working on.

She said: ''I like going! He comes to all my shows in Vegas. You know what I do? I get the little feed in my ear so I can hear him calling the game.''

Jimmy joked: ''Wow, you guys really are in love!''

While Jennifer is unsure how she'd fare if Alex seriously took her on in a race, the 'Shades of Blue' actress recently admitted her boyfriend was very impressed by her running speed.

She said: ''The other day, Alex was across the lawn, and I brought him something, and then I ran away.

''And he said: 'You run like you're 25 years old.' I haven't stopped that pace, so I'm still at that pace, I guess. When things start aching more, it'll be different.''

However, the brunette beauty - who has 10-year-old twins Max and Emme with her ex-husband Marc Anthony - understands that eventually time will catch up with her.

She explained: ''Listen, at some point, I'm going to age. They'll say, 'She looks old!' But, right now, I'm holding it together. I just take it day by day, because it's so much stuff, and I try not to worry about too much.''