BEIJINGSasha Artemev will replace injured Morgan Hamm on the U.S. men's gymnastics team.

The 22-year-old Artemev was chosen Thursday for the squad hours after Hamm withdrew because of a left ankle injury. Artemev is the second alternate to be put on the team. Raj Bhavsar replaced Morgan Hamm's twin brother, Paul, last week.

Artemev, the 2006 national champion, was the bronze medalist on pommel horse at the 2006 world championships but struggled with consistency at nationals and the Olympic trials, where he botched three of four routines. He was chosen over David Durante as Hamm's replacement and already was training in Beijing.

Gold in Beijing could help save Federer's season: Roger Federer is thinking more about the number eight than the No. 1 ranking he will lose after the Olympics.

The 12-time Grand Slam champion's birthday coincides with today's opening ceremony for the Beijing Olympics, which are being staged on one of the luckiest days in the Chinese calendar.

His more than four-year reign at No. 1 will end Aug. 18, regardless of how he fares in Beijing. Rafael Nadal earned enough points to overhaul the Swiss star.

The number eight has long been considered a good omen in China, where people pay a premium to have it included in their telephone numbers and license plates. With the official start of the 2008 Olympics on the eighth day of the eighth month of the eighth year, Federer is hoping some luck will rub off on him.

He has not won an Olympic medal in two previous trips, and for the first time since 2003 he has reached August without at least one major title for the season.

Zagunis: Two sabre gold medals "realistic": Mariel Zagunis doesn't mean to sound greedy or boastful, but her expectations for these Olympics are double what they were four years ago.

That means she would like to leave China with two gold medals in women's sabre.

"I believe in myself and I believe in my team," said Zagunis, who at the 2004 Games in Athens became the first U.S. fencer in 100 years to win an Olympic gold medal. "I think it's realistic to expect two golds. That's not to say it's going to be easy, but that's the mindset I'm taking."

Her historic victory four years ago made her a celebrity in the U.S. fencing community. It also made her a targeted opponent.

"It definitely makes people get more psyched when they go up against you," Zagunis said Thursday. "It means something for someone to say that they defeated the Olympic champion. But I don't mind that. I'd much rather have that pressure, than not." Economist says his formula can predict medal count: If you want to know how many gold medals the United States or competitors China and Russia will win at the Summer 2008 Olympics, don't ask the sports nuts. Talk to economist Daniel Johnson.

There's about a 95 percent chance he'll be right.

The Colorado College professor's mathematical formula — one based on factors such as wealth and politics, and not on athletic ability — has come eerily close to nailing down the final medal count for the last four Olympic games.

The model, which was concocted by Johnson and former student assistant Ayfer Ali in 1999 at Harvard, also considers a country's climate and the advantages of hosting.

This year, a booming economy and polluted air will help China take home the most gold medals — 44 to be exact. "China has the positive end of all the factors," said Johnson, citing better tolerance to pollution and the country's politics.

"Single regimes have done a better job at identifying athletes early," he said.

That may be true, but he still has the United States snatching up the most overall medals with a total of 103. They'll earn 33 golds this time around, while Russia will grab 28 gold medals and 95 total.