BEIJING (AP) - Chinese athletes won two gold medals Saturday on a first day of Olympic competition marred by the murder of an American volleyball coach’s relative and two doping controversies.

A knife-wielding Chinese man attacked two relatives of the coach at a tourist site in Beijing, killing one and seriously injuring the other, team officials said. The man then committed suicide by throwing himself from the second story of the site, the 13th century Drum Tower 5 kilometers (3 miles) from the main Olympic site.

"They are deeply saddened and shocked," U.S. Olympic Committee spokesman Darryl Seibel said of the volleyball team.

China quickly got on the gold medal tally board when Chen Xiexia won the women’s 48-kilogram weightlifting and 2006 world champion Pang Wei took the men’s 10-meter air pistol.

"I had low expectations of myself, but my coach and teammates created ideal conditions for me to win," Pang said.

Katerina Emmons of the Czech Republic had the distinction of winning the first of 302 golds to be awarded before the games end Aug. 24 when she took the 10-meter air rifle on Saturday morning.

There were also two positive doping tests involving Beijing-bound track athletes.

The Greek national Olympic committee said 29-year-old sprinter Tassos Gousis, who competes in the 200 meters, tested positive for the steroid methyltrienolone on Monday. He was sent home from a pre-games training camp in Japan after being informed of the result.

Russian steeplechase runner Roman Usov was pulled out of the games amid reports he failed a doping test conducted at the selection trials last month and only a week after seven female athletes from Russia were implicated in a doping scandal.

"The Russian track and field federation has made the decision that this athlete will not start in Beijing," Russian team spokesman Gennady Shvets told The Associated Press.

The 30-year-old Usov placed second at the national trials in Kazan, Russia, last month and had been listed to compete in the 3,000-meter steeplechase. Russian media reported that Usov had tested positive for the banned substance Carphedon.

Samuel Sanchez of Spain won the gold medal in the grueling men’s cycling road race that took the 143 competitors from central Beijing past Tiananmen Square, the Forbidden City and other landmarks before they rode out of the city for seven laps of a hilly loop course between two points on the Great Wall.

"It’s like a dream, I still can’t believe I’ve just won the gold medal," Sanchez said. "The heat and humidity were extreme."

In women’s basketball, Lauren Jackson, the WNBA’s most valuable player last year with the Seattle Storm, scored 18 points to lead Australia to an 83-64 win over Belarus.

There are later qualifying heats in swimming, where Michael Phelps will begin his quest for a record eight Olympic gold medals in the 400-meter individual medley. The final is Sunday morning.

Phelps was expected to be pushed by American teammate Ryan Lochte. The pair swam a memorable 400 IM final at the U.S. trials in June, when Phelps won in 4 minutes, 5.25 seconds, Lochte finished second and both went under world-record time.