DUHAMEL’S DADDY DUTIES

“Vegas” actor — sans wedding ring — was spotted collecting 4-year-old son

(above) after the tyke’s karate class in L.A.’s Brentwood. This comes on the heels of the surprising news that Duhamel and Black Eyed Peas singer were splitting after eight years of marriage. Meanwhile, Fergie made a sexy return to the stage in Brazil, where she performed at the Rock in Rio Festival.