LONDON - China surged clear at the top of the Olympic medals table on Sunday, adding two more golds to their opening day haul as swimming star James Magnussen put Australia on course for relay glory. After dominating day one of competition with four gold medals, Chinese athletes hit paydirt once again with wins in shooting for Guo Wenjun before synchronised divers Wu Minxia and He Zi triumphed at the Aquatics Centre.

Guo successfully defended her 10m air pistol title with a thrilling last-shot finish at the Royal Artillery Barracks to overhaul France's Celine Goberville, who had led going into the last round. "I just focused on doing my best on the final shot," Guo said, adding: "I think everyone is good, I just never give up."

Legendary diver Wu meanwhile clinched her third consecutive gold medal in the 3m springboard synchronised after wins in 2004 and 2008. Elsewhere Sunday the women's gymnastics competition was rocked by a failed drugs test, as organisers launched a probe into rows of empty seats at venues.

In the pool, American Dana Vollmer won the women's 100m butterfly Olympic gold medal Sunday clocking a world record of 55.98sec for a crushing victory over China's Lu Ying. Vollmer added the Olympic gold to the world title she claimed last year as she bettered the previous world record of 56.06sec set by Sweden's Sarah Sjostrom on July 27, 2009 at the World Championships in Rome. Lu came from fourth at the turn to take silver in 56.87 while Australia's Alicia Coutts rallied from last at the turn to take bronze in 56.94.

World champion Magnussen -- tipped to be one of the stars of the Games -- dived in at the last change to reel in US veteran Jason Lezak and lift Australia into Sunday night's relay final as top qualifiers. It was Magnussen's first swim at the Games and the 'Missile' delivered on his brash confidence, clocking a sizzling 47.35 seconds to surge past Lezak (48.04).

Sun Yang led the way into the men's 200m freestyle semi-finals just one day after he gave China it's first men's swimming title. US teenager Missy Franklin, swimming in seven events, was second-quickest. Uzbek gymnast Luiza Galiulina was provisionally suspended after testing positive for the banned diuretic furosemide, the International Olympic Committee (IOC) announced. Galiulina underwent a drugs test on July 25, three days before the start of the women's artistic gymnastics competition.

The hosts suffered another blow when women's marathon world record holder Paula Radcliffe withdrew from the Games because of injury. The hosts' best next hope may be in the pool where Rebecca Adlington defends her 400 freestyle title, although she scraped into the final as the slowest qualifier. Adlington is up against Italian world champion and world record holder Federica Pellegrini and world number one Camille Muffat of France.

Day Two saw the latest incarnation of the U.S. basketball "Dream Team", this time featuring LeBron James, Kobe Bryant and Kevin Durant, begin their title defence with a comfortable 98-71 win over France after a joyful display of high-flying skill. Four years after China put an over-time scare into Spain's NBA-laden silver medal Olympic squad, Los Angeles Lakers star Pau Gasol and his Spanish teammates made certain it would not happen again. Gasol scored 21 points and grabbed 11 rebounds to spark the Spaniards over China 97-81 on Sunday in their Group B round-robin men's basketball opener, even though NBA standout Yi Jianlian pushed the European champions to the end.

Hungary's Aron Szilagyi won the Olympic Games men's fencing sabre gold medal, beating Italy's Diego Occhiuzzi 15-8 in the final. Russia's Nikolay Kovalev defeated Romania's Rares Dumitrescu 15-10 for bronze.

   Medal Table

Rank    Country    Gold    Silver    Bronze    Total

1    China    6    2    2    10

2    Italy    2    3    2    7

2    United States    2    3    2    7

4    South Korea    2    1    2    5

5    Kazakhstan    2    0    0    2

6    Brazil    1    1    1    3

6    Hungary    1    1    1    3

8    Netherlands    1    1    0    2

9    Russian Federation    1    0    2    3

10    North Korea    1    0    1    2

11    Georgia    1    0    0    1

11    Australia    1    0    0    1

13    Japan    0    2    3    5

14    France    0    1    1    2

15    Colombia    0    1    0    1

15    Cuba    0    1    0    1

15    Romania    0    1    0    1

15    Poland    0    1    0    1

15    Chinese Taipei    0    1    0    1

15    Great Britain & N. Ireland    0    1    0    1

21    Ukraine    0    0    1    1

21    Uzbekistan    0    0    1    1

21    Moldova    0    0    1    1

21    Belgium    0    0    1    1

21    Serbia    0    0    1    1

21    Slovakia    0    0    1    1

21    Norway    0    0    1    1

21    Canada    0    0    1    1