Britney Spears' estranged husband Kevin Federline took their two young sons to Las Vegas over the weekend (ends04MAR07) - for a promotional appearance at a nightclub.
Federline is watching the couple's children Sean Preston, 18 months, and JAYDEN JAMES, six months, while Spears is seeking treatment in rehab.
Federline was in Las Vegas for a long-planned paid appearance at the Mirage Hotel + Casino lounge Revolution.
A source tells American publication People, "Kevin was really low-key. You could definitely tell he was on his best behaviour.
"He was having a good time, but wasn't the wild, crazy Kevin who used to come to Vegas."
The former back-up dancer arrived on Saturday (03MAR07), along with an unusual entourage, featuring a nanny, his mother and brother and two bodyguards.
Although he was in town for a party appearance, Federline appeared to have his priorities straight.
The source adds, "He was late for dinner (with friends and family) because he wanted to tuck his kids into bed."