By Julian Linden
LONDON (Reuters) - Sun Yang and Ryan Lochte provided a mouthwatering appetizer ahead of the most anticipated race of the Olympic swimming competition when they posted the fastest qualifying times for the men's 200 meters freestyle on Sunday.
The pair, who each won gold medals on the opening night of swimming, both qualified for the semi-finals without exerting too much energy but gave a sneak preview of what Monday's final could offer when they went stroke for stroke over four laps during an exhilarating morning heat session.
Britain's Rebecca Adlington, the great hope of the Olympic host-nation in the swimming pool, gave her supporters some anxious moments before scraping into the final of the women's 400 freestyle.
The crowd at London's Aquatic Centre roared with delight when the Beijing champion won her heat but the cheers soon gave way to fears as the swimmers in the following heats began posting faster times.
There was relief when Adlington made it through to the final, albeit as the eighth and slowest qualifier.
"It felt faster," Adlington said. "You just don't know being in the first (seeded) heat. I had no option, I just had to go for it."
Italy's Federica Pellegrini, the reigning world champion and world record holder, also flirted with danger but finished seventh overall with France's Camille Muffatt setting the fastest time.
American Matt Grevers posted the fastest time for the men's 100 backstroke while Lithuanian teenager Ruta Meilutyte provided her older and more experienced rivals with an ominous warning when she topped the women's 100 breaststroke heats.
Australia's Leisel Jones, the Beijing Olympic champion who also won a silver at the 2000 Sydney Games when she was 15, finished second in the same heat while American Rebecca Soni, the world champion and favorite to win the gold, was second overall.
"It's great to see when someone (Meilutyte) swims faster than they thought they could," said Soni. "That joy rubs off on the rest of us."
Crack Australian sprinter James Magnussen took his first plunge into the Olympic pool, anchoring his team mates to the fastest time in the 4x100 freestyle relay, just ahead of the United States.
The Americans face a difficult decision picking their lineup for the final with Michael Phelps and Lochte, who did not swim the event at the U.S. Trials, likely to be called up.
"There could be a lot of politics but our team is pretty mature - we understand the coaches probably know best," said Matt Grevers, who swam in the heats.
Australia's Emily Seebohm, still riding a wave of excitement after winning a relay gold medal on Saturday, upstaged American teenager Missy Franklin to head the women's 100 backstroke.
Seebohm came agonizingly close to breaking the world record when she won her heat in 58.23 seconds, just 0.11 outside the mark, relegating Franklin, the rising star of the American women's team, to second overall.
"Emily's race was unbelievable but I have no control over her and what she does," Franklin said. "The only thing I can control is myself."
CAT AND MOUSE
Swimming in the lanes next to each other, Lochte and Sun treated their heat like a game of cat and mouse, eyeballing each other over the first three and a half laps before shifting up another gear in the last 25 meters.
China's Sun, who won the 400 freestyle gold medal on Saturday, got his hand on the wall first in a time of one minute 46.24 seconds with Lochte a close second.
But neither man was trying their hardest as they try to manage their busy programs. Lochte was in hot demand after he demolished his opponents, including Phelps, to win the 400 individual medley on Saturday.
"The 400 IM took a lot out of me last night but it is a new day," Lochte said. "I didn't get to bed until 2am."
South Korea's Park Tae-hwan was fifth fastest. He finished runner-up to Sun in the 400 free after being disqualified in the heats but winning an appeal to be reinstated.
Germany's world record holder Paul Biedermann was 10th. Phelps, who won the race in Beijing four years ago, did not enter this time despite winning the event at the U.S. trials, saying he wanted to save himself for the relay.
(Editing by Greg Stutchbury)