Swimmers Michael Phelps and Dara Torres, gymnasts Shawn Johnson and Nastia Liukin, beach volleyball players Misty May-Treanor and Kerri Walsh and others joined Winfrey to tape her season premier of "The Oprah Winfrey Show."

 

The show, which will be broadcast next Monday, was also a welcome home for the United States team that had competed in the Beijing Olympics.

 

But mainly it was to provide a high-profile opportunity to publicise Chicago's bid to bring the Summer Games back to the US for the first time since Atlanta in 1996 and to follow London.

 

"Great city, my kind of town, Chicago," Winfrey yelled before the 6,000 fans who crammed into Millennium Park drowned out part of a sentence that ended with the words, "come to Chicago for the 2016 Games."

 

The 54-year-old Winfrey, whose career started in Chicago and who retains a residence there,  is hugely influential in the US and her endorsement of a product or cause can make-or-break it.

 

Winfrey's fans said they have no doubt that the billionairess talk-show star can help bring the Games to Chicago.

 

"I think a lot of people watch, lots of people admire her and she's a good promoter for Chicago," said David Ritchie, 56, who came from his home in the Dallas area to watch the show.

 

One fan sounded amazed that anyone could even wonder if Winfrey had that kind of clout.

 

"Well, she's Oprah, she can do whatever she wants, basically," said Deb Ullrich, who flew with her niece for the show from Columbus, Ohio.

 

Organisers for the city's bid certainly hope so.

 

Chicago 2016 spokesman Patrick Sandusky said: "Oprah is a global icon and a global Chicago icon.

 

"So, for her to embrace the Olympic movement like this, it only helps us in a fantastic way."

 

That sentiment was shared blocks away by people heading to their jobs.

 

"Look what she did for Barack Obama," said Robert Casillas, a 37-year-old banker from suburban Chicago .

 

"Hosting that party put him over the top," he said, referring to the fundraiser Winfrey hosted for the Democratic presidential hopeful last September at her California home.

 

"And endorsing (Obama) put other people on the bandwagon."

 

Harpo Productions says Winfrey's programme airs in 140 countries, including Spain and Brazil, but not in Japan.

 

At the taping, Winfrey played video clips of some of the Games' most memorable moments.

 

There on the screen, with the crowd cheering as if they were watching it live, was Phelps' come-from-behind win in the 100 metre butterfly in Beijing, Jason Lezak chasing down France's Alain Bernard to give the Americans the gold medal in the 4x100m freestyle relay.

 

They roared as Shawn Johnson won the gold medal in the balance beam and did the same as Sanya Richards pulled off her own come-from behind victory in the women's 4x400m relay.

 

Chicago are bidding against Madrid, Rio de Janeiro and Tokyo.

 

The International Olympic Committee will choose the Host City at its Session in Copenhagen on October 9, 2009.