Dallas Cowboys Legends -- We're Soccer Dads Now ... Our Daughters Are Ballers!

Three Dallas Cowboys legends are back on the same sideline ... rooting on their daughters who all play in the same elite youth soccer league ... TMZ Sports has learned.

Emmitt Smith, Tony Dorsett and Charles Haley -- together they have 9 Super Bowls, 17 Pro Bowls and 2 Hall of Fame busts -- and they get together every weekend as soccer dads.

"[Our daughters] are out there ballin', Dorsett tells us ... "The apples don't fall far from the tree."

Tony -- who was inducted into the Hall of Fame in '94 -- says his daughter plays on the same team with Haley's kid ... and even though Emmit's daughter plays on another squad, "They go head to head sometimes."

"When we're together, we talk about football. It's not usually about the old days. We talk about what's going on in the league now," Dorsett says.

Tony says the guys are all very supportive of each other's kids -- "All of the girls are very talented" -- but says Charles' daughter is a star among stars.