By Martyn Herman

LONDON (Reuters) - Reigning women's volleyball champions Brazil prevailed in a late-night thriller against newcomers Turkey at Earls Court to complete a sizzling opening day of preliminary round action at the London Games on Saturday.

Brazil eventually edged home 3-2 in a match full of spellbinding rallies played out in front of raucous crowd liberally splashed with yellow and green, and red.

It was just a shame that thousands of neutrals had already departed to dash for trains home as the opening volleyball games stretched Day One of the Olympics way into Day Two.

Earlier the United States, loaded with multiple Olympians who are still seeking an elusive gold medal, fought off a tenacious South Korea 3-1 in another classic Pool B contest.

World champions Russia, with Prime Minister Dmitry Medvedev among the 15,000 fans, beat Britain 3-0 in Pool A in the host country's first appearance in indoor volleyball at the Olympics.

There were also wins for China over Serbia in Pool B while Japan eased past Group A rivals Algeria in the day's opener. Italy struggled to beat Dominican Republic 3-1 in Pool A.

If Brazil do retain the trophy, skipper Fabiana Claudino and her team will surely not have many tougher tests than posed by Turkey, who have become a genuine medal threat under Brazilian coach Marco Motta.

"We knew it was going to be like that, it's the Olympics and every game is like a final," Turkey-based Fabiana, appearing at her third successive Games, told Reuters.

"It was a great match and I think we played well. I never really thought we would lose. But we were anxious."

"The crowd were amazing to see so many Brazilians supporting us, it helped a lot."

WORKED HARD

The U.S. women's team, who face Brazil in a mouth-watering repeat of the 2008 final on Tuesday, were captained by Lindsey Berg, veteran of two previous Olympics, and also included Logan Tom, competing at her fourth Games in their line-up.

Both are seeking to win a long-awaited Olympic gold medal after falling short four years ago when they were beaten by the Brazilians in the final in Beijing.

With the explosive outside hitter Destinee Hooker, making her Olympic bow, finding the target with some ferocious spiking, the Americans won the first two sets 25-19 25-17 but South Korea hit back to win the third 25-20.

However, Hugh McCutcheon's team re-asserted their authority to finally subdue the Koreans, winning the fourth game 25-21 to end a compelling two-hour contest.

"Congratulations to Korea, they really made us work. We had to be on our toes, they made us work for everything," Berg told reporters. "I thought the girls at their first Olympics came out and really played volleyball."

New Zealander McCutcheon, who coached the American men to gold in Beijing, said he knew his side were in a tough pool.

"We get a day to re-group and get ready for the next game. They (Korea) are a tough team, well-coached with a lot of skill. It's a dangerous group so we are pleased with the win," he said.

The American women are not the only ones seeking a precious gold medal. Russia's 37-year-old spiker Evgenia Estes, playing at her sixth Games, has three silvers from 1992, 2000 and 2004, but has never topped the podium.

She said she feels Russia have every chance this time, especially with the imposing Ekaterina Gamova in their ranks.

"I have won three silver medals but I would like to add a gold," she said. "I expect our toughest opponents will be the United States followed by Brazil."

The first four teams from each pool progress to the quarter-finals. Men's action begins on Sunday.

(Editing by John O'Brien)