PHOENIX – Fathers teach their sons.

But Shane Mosley wasn’t prepared to teach his son about defeat Saturday night.

Shane Mosley Jr. tasted defeat in only his third pro bout at Celebrity Theater, losing a split-decision to Marchchristopher Adkins in a four-round junior middleweight bout.

Mosley Jr. (2-1, 2 KOs) wobbled Adkins (3-1, 2 KOs), of Dallas, with a counter right in the opening round. But he failed to capitalize and appeared to tire over the next three rounds, losing 39-37 on two of the three cards. The third card favored Mosley Jr., by the same score

“I thought he won the fight,” said the senior Mosley, a former champion at three weights who was assisted in the corner by his own dad and former trainer Jack Mosley. “I thought that maybe he got overexcited and tried to land one big shot. He can punch. I’ve sparred with him a few times.

“It hurts, because this really was a fight he should have won. But we’ll go back to work. You learn from these things. I’ve been through them. I told him you just can’t leave it up the scorecards like that. But when you lose one you really should have won, it just makes it that much tougher.”