Every few weeks, Williams-Webb meticulously selects outfits for Anthony, down to his socks, underwear, belt and shoes. She then places each outfit into a garment bag, with instructions for Anthony pinned to the bag. She sometimes arranges more than a dozen outfits at once.

Anthony was not available to comment for this article, his representative Jill Fritzo said. Fritzo added that she, too, was a fan of Wiliams-Webb, saying in an e-mail, “She’s fab.”

Williams-Webb’s client list includes the N.B.A. players Rudy Gay and Brandon Bass and the N.F.L. player Donte Whitner and the former player James Hardy. She spends her days shopping, meeting with designers and hunting for extra-long pants and size 14 shoes. It is all a long way from her years working in retail in Midtown Manhattan.

“She totally got the athlete lifestyle,” said Hardy, a former receiver with the Buffalo Bills who is a model and an actor in Los Angeles. “You called and asked her about the Kanye West shoes, and she would have them at your door in 48 hours and knew about them weeks in advance.”

In 2005, the N.B.A. instituted a dress code that banned tank tops, sweats and chunky medallions in favor of sport coats and dress shoes. The unintentional effect has turned the sidelines into a runway.

“It’s different now,” Williams-Webb said. “Basketball players are into it, athletes in general are into it. They’re into clothes, they’re into suiting.”