Sightings: Lopez, Lachey and Richie

Jennifer Lopez gets back to work. Nick Lachey gets private. And Nicole Richie goes for Mexican. Time for celeb sightings!

WORKING MOTHER: Jennifer Lopez, leaving the babies at home while conducting a business lunch at Orso in Los Angeles.

OH, REALLY: Sandra Oh, having dinner at Real Food Daily on La Cienega Boulevard in L.A.

SOUTH OF THE BORDER: Nicole Richie and Joel Madden, making a late-night stop at Mexicali in the Studio City area of L.A. for cerviche and enchiladas.

SOUND OF MUSIC: Samantha Ronson and DJ AM, taking the same flight from New York to Los Angeles last week.

BIG GULP: John Leguizamo, downing Cabana Cachaça cocktails at Hamptons and Gotham magazines’ summer kickoff party at Mansion in NYC.

RICO SUAVE: John Legend, hanging at the El San Juan Hotel and Casino in Puerto Rico.

NEW COUPLE? Fantastic Four hottie Chris Evans and Laura Prepon, getting cozy in the Hennessy Lounge at the Maxim Hot 100 party on the Paramount lot in Hollywood, while Nick Lachey demanded that photographers not take his picture.

CHORUS GIRL: Amy Adams, chatting with George Takei at the opening of A Chorus Line at the Ahmanson Theatre in L.A.