China's Jiao Liuyang produced a powerful last lap to come from behind and beat Spain's Mireia Belmonte Garcia in the final of the women's 200 meter butterfly.

Jiao Liuyang performs in women's 200m butterfly at London Olylmpics on August 1, 2012. [Xinhua]

Jiao had won silver in Beijing and this time went one better, while Japan's Natsumi Hoshi was third. Belmonte, meanwhile had the honor of claiming Spain's first medal of these Games in any event.

"I am really happy, I have waited for this goal for four years. Four years ago I was trying to play catch-up all race, but this time I was in the lead, I think all of the swimmers are very good and anyone has done well to get on the podium" said Jiao.

Nathan Adrian beat Australia's James Magnussen by one hundredth of a second to win the gold medal in the final of the men's 100 meters on Wednesday.

Adrian got the better touch on the wall to edge out the Australian, who had looked set to claim the gold medal, before a dramatic finish in which Canadian veteran Brett Hayden was third in his third appearance at an Olympic Games.

Just nine tenths of a second separated all eight races in which the lead changed hands on several occasions.

Magnussen had led in the opening meters, before Cielo threatened to produce a winning performance only to fade away as Magnussen again pressured.

However, the only time you actually have to lead a race in order to win is when you race the finish and that is when Adrian made his move.

"It's pretty amazing seeing a one next to your name. I almost started crying in the water. This is something that happens every four years. It's not who swims the fastest time this year but it's who can get their hands on the wall first here tonight,"

Hungarian Daniel Gyurta set a new world record of 2:07.28 as he won the gold medal in the men's 200 meters breaststroke on Wednesday.

The European record holder and reigning world champion led from the front, but had to fend off a powerful fightback from Britain's Michael Jameson in the final lap.

Gyurta's is the fourth world record that has been set at these Games, following Ye Shiwen's triumph in the women's 400 meters medley, American Dan Vollmer in the women's 100 meters butterfly and Cameron van der Burgh in the men's 100 meters breaststroke.

"Of course I'm proud of the Olympic title. To break the world record is what makes me proudest. I managed to prove for everyone and for myself that I could bounce back and do what I dreamed of since my childhood," said Gyuta.

Jameson claimed Britain's second medal in the pool following Rebecca Adlington's bronze in the 40 meters freestyle on Saturday.

"I have received so many messages of support and I was determined to get on the podium to thank everyone for that. It was a lot easier to swim tonight with a bit of confidence back," said Jameson.

The day ended with 200 meters individual freestyle gold medalist Alison Schmitt swimming a phenomenal final leg to give the US the gold medal in the women's 4x200 meters relay on Wednesday and shave almost one and a half seconds off the Olympic record with a time of 7:42.92.

Schmitt was simply too strong for Australian Alicia Coutts over the final 200 meters and despite having started her leg with a slight led, Coutts and her companions had to settle for silver, while the French took bronze.

The Chinese went into the race as the world record holders, with a team of Ye Shiwen, Wang Shijia, Liu Jing and Tang Yi but could only finish sixth.

Missy Franklin gave the American's a strong leadout but tired in the last lap and was overhauled by Australian Barratt Bronte and Frances' Camille Moffat, although the race soon boiled down to the traditional battle between Australia and the US.

Kylie Palmer worked tremendously hard to try and give Alicia Coutts a lead to take against Schmitt but that soon evaporated as Schmitt began powering her way to victory and her second gold medal of these Games.

"I knew Allison was going to pull off something amazing and the rest of us had to at least be even with everyone else, knowing that I fought as hard as I could that last 50 (meters) to either get ahead or at least stay even with the field so every person diving in would have the best chance they could," said Dan Vollmer, who swam the third leg for the US.

The drama was not just confirmed to the finals, however, as Rebecca Soni set another new world record in the second women's 200 meters breaststroke semifinal. Soni swam her heat in 2.20.00 and five world records have now fallen in London.

The American dominated her heat and made no attempt to save energy ahead of the final and her qualifying time was almost a second and a half than the second fastest person into the Rikke Piedersen.

"I didn't feel any pressure, I just wanted to see how it went, so I just went for it," she explained

Ryan Lochte finished ahead of Michael Phelps in the first semifinal of the men's 200 medley with Britain's James Goddard third. Both Americans eased off in the closing meters, but Phelps is on course for a 20th Olympic medal on Thursday.

Phelps said he and Lochte had enjoyed watching Adrian's 100 meters triumph.

"We were both cheering like crazy. We have had a great week so far, but we said at a team meeting that it is only halfway done," said Phelps, who added he enjoyed facing Lochte.

"We love racing each other, Neither of us likes to lose, I like to say we bring the best out of each other."

Laszlo Cesc finally found some form in the second semifinal, qualifying with a time that was faster than Phelps.

The 2008 gold medalist and reigning world champion, Lochte won his first semifinal of the night in the men's 200 meters backstroke, enjoying - a smooth swim ahead of Irie Ryosuke of Japan.

They were joined by Tyler Clary, who won the second semifinal with China's Zhang Fenglin in second place ahead of Kazuki Watanabe.

"I need to work a bit on my turns and breakout, but I think tomorrow's going to be a pretty good swim," commented Clary.

Ranomi Kromowidjojo set an Olympic record of 53.05 in qualifying for the final of the women's 200 meter freestyle. China's Tan Yi also swam solidly, finishing first in the same semifinal to qualify for Thursday's final with the fourth fastest time, while Missy Frankin can enjoy another final after finishing third overall.

"I am feeling pretty good," said Kromowidjojo afterwards.