Justin Timberlake and Garth Brooks

A May-December bromance is brewing between Justin Timberlake and Garth Brooks, sources dished – and it’s all about the babes, as in babies!

Justin has been eager to “pick Garth’s brain” for career advice, insiders said. But Garth, 52, urged the dad-to-be, 33, to hold his horses.

“He told Justin, ‘I see myself when I look at you, kid, my old self,’” a source said.

“Garth told Justin how he used to believe as long as he gave his family a great living, that’s all he needed to do, and it ended up destroying his first marriage.”

Garth split from his wife, Sandy, in 2001. Soon after, he announced he was retiring to focus on raising the couple’s three daughters. He married singer Trisha Yearwood in 2005, and resumed recording and touring in 2014.

Meanwhile, Justin and wife Jessica Biel expect their first child this summer. JT first bonded with Garth after attending his concert on Dec. 4 in St. Louis.

“Garth told Justin he’s got to keep his eyes on the prize, and that prize is his family,” the friend added.

“He told Justin not to make the same mistakes he made years ago. I think it got Justin to thinking about how his life will change with the new responsibility he’s about to take on.”