This year’s U.S Open has witnessed the return of the tennis diva – the skimpy outfits, the temper tantrums, the Hollywood-style book signings. After years of Sampras doldrums and Agassi-zen, the tennis world was jonesing for some McEnroe-style fire again. But who has emerged as the leader of the pack?

Is it Nicolas Massu, the Chilean double gold medalist, who trashed two rackets in his second-round loss to Sargis Sargsian last week? So upset was Massu with the chair umpire – who penalized Massu for his tantrums, costing him the match – the medalist fumed, “This guy’s unbelievable. He’s never going to umpire me again.”

Or is cocky Andy Roddick the worst offender? The enfant terrible of American tennis broke a racket last Thursday – not in a match, but in his very public (and shirtless) practice with coach Brad Gilbert as the adoring fans egged him on. Roddick, too, excoriated an umpire over questionable calls during his second round match, despite winning in straight sets.

“Something about a night session at the Open that kind of gets inside you a little bit,” Roddick explained after the match. In Roddick’s case, the conniption fits only endear him more to the crowd.

But no diva cheat sheet would be complete without Serena Williams. The former no.1 player has her sights set on Hollywood, hanging out in Cannes rather than prepping for the French Open, trying to pick up acting tips from the likes of Tom Hanks. In the process, she seems to have picked up some prim Donna tactics that her older, humbler sister, Venus, has managed to avoid.

“I always considered myself as an entertainer,” Serena said after her second-round match. “I remember always thinking of myself as a broader picture as opposed to just your normal athlete. I don’t think I’ve ever been your normal athlete. I’ve always had something different going on in my life.”

Naomi Campbell showed up for Serena’s match on Sunday, and the runway diva seems to have been passing along fashion tips to Williams, whose outrageous apparel has been the talk of the tournament. Monday’s outfit, a studded belly shirt and black bikini shorts, may be the most revealing outfit in Open history, despite Serena’s protestations to the contrary.

“I didn’t consider it skimpy,” she told reporters. “It’s really sexy and micro-mini.” Whatever. The outfit was racy enough to make Serena’s Friday apparel – a black one-piece with a flirty skirt, accessorized, again, with studs – look positively demure. “It was chilly,” Serena explained of the more conservative look.

But it’s not just the wardrobe that’s been showing Serena’s diva stripes. When the temperamental star dropped her racket after a tough point in her second-round match Friday night, she walked away in frustration before turning to glare at the ball girl.

“What are you waiting for,” her glare seemed to say. “Pick the racquet up.” And the ball girl did.

Saturday afternoon, Serena was scheduled to appear at 1:15 at the U.S. Tennis Center Bookstore to sign copies of her new book, “How to Play Tennis.” By 1:45, more than a hundred people were lined up in the hot sun to nab her signature. But Serena was nowhere in sight.

“I guess she comes when she wants to come,” groused a Maria Shriver look-alike, standing off in the shade, hand on hip. Meanwhile, a USTA representative approached those in the back of the line to explain that the tennis star might not have time to meet with everyone. “She might want to stay, but she’s not obligated to.”

Not everyone was peeved with Serena’s lateness. Mike Freidman, 14, had flown in from Nebraska for the Open and was perusing a copy of Williams’s new book. He wasn’t entirely impressed with the tome. “It’s a lot of basic stuff,” said Friedman, who had braces, a face full of freckles, and a sunburned nose. But he was excited to meet Serena just the same. “She’s awesome.”

By 1:55 p.m., Ken Shell, 37, had been waiting for an hour and was about to leave. Then he spotted Serena, her long mane of curly amber hair identifying her among a bevy of yellow-shirted security guards. The crowd cheered as she walked past them. After giving the crowd a few desultory waves, Serena lifted her head and smiled wanly in the crowd’s direction, as if warming her face in their adulation.

What is it you love about Serena? I asked Shell. “Her style, her passion, her attitude, her presence,” he listed in quick succession.

Was he upset by Williams’s lateness? “I just figured, you know, that she has a lot going on right now.”

Indeed, she does. Williams also kept fans waiting before her second-round match while a handler retrieved her purse. “I was hitting warm-up and I realized I didn’t have my earrings on,” she explained afterwards.

Were the missing earrings a distraction? “No, not a distraction,” she replied. “I just really believe in accessorizing. Most people see me on the tennis court, and a lot of people don’t see me elsewhere. That’s where I’m mostly photographed at. I think it’s important for me to look the best I can.”