LONDON — Mick Jagger has dropped by Olympic Stadium to watch some track and field, providing relief to celebrity-watchers worried that the world’s biggest sporting event has been a little lacking in star power – off the field, that is.

The Rolling Stones singer, photographed Monday chatting with London organizing committee chief Sebastian Coe at the stadium, is not the only A-lister to take in the games. But most are keeping a low profile.

It’s as if they know that for this brief period, they’re not the stars. The athletes are.

“My advice would be, go on holiday for two or three weeks,” PR guru Max Clifford advised celebrities.

“I think the danger is that they could be seen to be cashing in, and the public would find that offensive,” he said. “And it would remind people how empty most of them are.”

The London games have played to huge crowds, dozens of dignitaries and a healthy sprinkling of royalty, with Prince William, his wife, Kate, and Prince Harry popping up at everything from swimming to sailing to gymnastics to cheer on the British team.

Former U.S. Secretary of State Condoleezza Rice was spotted at the Olympic Stadium on Tuesday, and actress Susan Sarandon watched men’s water polo alongside gold medalist Carl Lewis on Monday. Billionaire Bill Gates has attended events including table tennis and beach volleyball.

But megastars have been few and far between. Nicole Kidman went to the opening ceremony – “Wow!” was the reaction posted on her Facebook page – and attended a party at the Omega House hospitality venue as a face of the watch brand.

Paul McCartney, who sang “Hey Jude” at the opening ceremony, has shown up several times at the Olympic Stadium and the Velodrome.

But Brad Pitt and Angelina Jolie, both filming in Britain this summer, have gone undetected at the games and in London nightspots – to the regret of the world’s paparazzi.

One deterrent to an Olympic visit could be the concentration in one spot of thousands of the world’s media.

While it’s fairly easy for the rich and famous to blend in amid the hordes visiting Olympic Park, there’s no skipping Olympic security – even if you’re a star or the fastest man on Earth. Sprinter Usain Bolt complained about being told to stand in a straight line and not being allowed to take his jump rope and iPad through security.

No surprise, then, that many stars have chosen to enjoy the Olympics from afar and offer virtual support to their favorite athletes on Twitter.

Samuel L. Jackson has been the most prolific, live-tweeting nearly every event and cheering on competitors from around the world in a riot of capital letters and creative language.

Jackson was among the many stars who congratulated Venus and Serena Williams on their gold medal in doubles tennis, tweeting: “Gotta give Late Props to VENUS & Serena! TREYPEATING GOLD!!! Midas ain’t got Nothing on Y’all!! Go USA!!”

Swimmer Michael Phelps and gymnast Gabby Douglas were hailed by everyone from Lil Wayne to Michelle Obama, while American gold medal swimmer Missy Franklin, 17, received a special tweet from her celebrity crush, Justin Bieber.

“Heard @FranklinMissy is a fan of mine. now im a fan of hers too. CONGRATS on winning GOLD! #muchlove,” the pop star posted.

Franklin was impressed. “I just died!” she tweeted back. “Thankyou!”

It’s a sign of the times to see celebrities praising athletes, even those largely unknown outside their disciplines just weeks ago.

The games have brought an Olympian round of soul-searching about the nature of fame. A mood has swelled that – never mind professional athletes and overpaid actors – Olympic champions should be the real celebrities.

Clifford predicted that the status quo soon would return once the games end on Sunday.

Editors “can’t fill the papers with stories of Olympians every week, because Olympians aren’t publicity-conscious,” he said. “Most of them are quite shy and retiring.”

Celebrity, he added, requires a certain shamelessness.

“ ‘Respect’ is not a word you tend to think of” with many celebs, Clifford said. “But with Olympians, you do.”

AP writer Sandy Cohen in Los Angeles contributed to this report.