Lithuanian teenager Ruta Meilutyte has caused one of the biggest shocks of London 2012 so far after the unheralded athlete stunned a world-class field in the women's 100 metres breaststroke final to claim her country's first ever Olympic swimming medal.

The victory makes Meilutyte (pictured top, in green cap) the youngest ever winner of the discipline at 15 years 133 days old as well as the youngest Olympic champion in any swimming event since American Beth Botsford triumphed in the 100m backstroke at Atlanta 1996 aged 15 years 62 days.

Meilutyte, originally from Kaunas but who now lives in England and attends the same Plymouth school as British diver Tom Daley, led from the start and miraculously held on to claim gold ahead of American superstar and reigning world champion Rebecca Soni by the narrowest of margins.

The teenager finished in a national record of 1min 05.47sec while Soni, the overwhelming favourite going into the race, finished just 0:08sec behind in 1:05.55 to claim silver, the same colour medal she won in the event in Beijing four years ago.

Japan's Satomi Suzuki earned bronze in 1:06.46 while Australia's defending Olympic champion, Leisel Jones, finished fifth.

But the race undoubtedly belonged to Meilutyte, who was completely overcome with emotion following the unlikely win on the biggest stage in sport.

"I can't believe it," she said through tears.

"It's too much for me.

"I really can't say anything.

"It was hard and difficult.

"At the moment I can't speak too much but it means a lot to me and I'm so proud."

Meilutyte's tears of joy continued on the podium in what marks a remarkable journey for the teenager, who only turned 15 in March.

She moved to Britain three years ago with her father and is trained by English coach Jon Rudd.

Rudd knew he had a major talent on his hands when he first saw Meilutyte but admitted the result was a major shock.

"We didn't realistically know what she would do but the Olympics are a funny place," he said.

"She is a talented and vigilant worker but this is obviously unexpected."

Meilutyte proved she was not at the Games just to make up the numbers by setting a European record in the heats which proved two seconds faster than her personal best.

She swam even quicker in the semi-finals yesterday to qualify fastest for the final and managed to hold her nerve even through a bizarre fault at the start when the bleep went off before the swimmers were told to take their marks.

The long delay should perhaps have favoured more experienced competitors but Meilutyte kept her composure to astonish both herself and the crowd to win.

Soni sportingly led the tributes to the Lithuanian.

"You have to give her credit because what she has done is phenomenal," said the American.

"I'm a little disappointed not to win gold but to do what she did at her age is pretty special."

Meilutyte could actually add to her medal tally at the Olympics as she is also competing in the women's 50m and 100m freestyle events and will now be taken seriously by her competitors following the shock gold.

It marked Lithuania's first gold medal of London 2012 and only its fifth ever.

The first was won in the men's discus by Romas Ubartas, who claimed victory at Barcelona 1992, four years after winning a silver medal for the Soviet Union at Seoul in 1988.

The second also came in the men's discus, at Sydney 2000 courtesy of Virgilijus Alekna, while at the same Games, Daina Gudzinevičiūtė took victory in the women's trap shooting.

Alekna again won the men's discus at Athens 2004 while Meilutyte becomes Lithuania's first swimming gold medallist.

By Tom Degun at the Aquatics Centre on the Olympic Park in London