LONDON Swimming's biggest names slug it out in the Olympics men's 200 meter freestyle on Monday, as China extended its lead in the medals table and Swiss soccer player Michel Morganella was expelled for an abusive message on Twitter.
The row over empty seats at venues across London rumbled on, but the weather was cool and sunny and London's transport system largely defied predictions of gridlock on the first regular working day of the 2012 Games.
With British Prime Minister David Cameron looking on, China's Cao Yuan and Zhang Yanquan won the men's synchronized 10 meter platform diving and extended the host nation's wait for its first gold of the Games after Tom Daley and Pete Waterfield could only manage fourth.
Romania took its first gold with Alin George Moldoveanu's surprise victory in the 10m air rifle event, and on a packed day of sport Russia's Mansur Isaev triumphed in the 73kg men's judo after a fast and furious fight with Japan's Riki Nakaya.
Olympic organizers were under pressure again to fill arenas and placate a public furious at seeing TV pictures of unused places, having been told months ago that venues had sold out.
They have laid the blame chiefly with foreign teams, their officials and governing bodies of various sports who have between five and 15 percent of seats made available to them.
Cameron said volunteers, soldiers and the public would be able to take some of the slack, but added: "You'll never have complete eradication of empty seats."
Ticketing confusion also led to the opposite problem - overcrowding - in at least one instance on Monday.
Dozens of angry ticketholders trying to get into the men's 10m air rifle competition at Royal Artillery Barracks were turned away because the venue was too full.
London's transport bosses expect an extra three million journeys per day on top of the usual 12 million during the Games, an Olympian test for an underground train network that first opened in 1863 during the reign of Queen Victoria.
But on the first morning rush hour since the Games opened on Friday night, commuters said buses, trains and the metro were working surprisingly smoothly with a few hiccups, and roads were generally clear.
Chris Round, 23, from Boston, Massachusetts, took the Underground and Docklands Light Railway to watch the judo.
"It was real easy to get to," he said. We just got on the first train that came. It was kinda crowded but it wasn't bad."
Later on Monday American Ryan Lochte, Sun Yang of China and France's Yannick Agnel were due to chase a second London gold in one of the most anticipated races in the pool, the 200 freestyle.
Lochte won gold in the 400 individual medley, trouncing his compatriot Michael Phelps, Sun triumphed in the 400 freestyle and Agnel beat Lochte to clinch a shock gold for France with a devastating surge on the last length of Sunday's 4x100 relay.
Monday's race also includes world record holder Paul Biedermann of Germany and South Korea's Park Tae-hwan, a line-up that could decide bragging rights over who is the best male swimmer at the Games.
Also up for grabs are the men's 100 backstroke, where Matt Grevers of the U.S. qualified fastest, the women's 100 backstroke where Australia's Emily Seebohm almost broke the world record in qualifying, and the women's 100 breaststroke in which 15-year-old Lithuanian Ruta Meilutyte leads the field.
On Sunday, South Africa's Cameron Van der Burgh and American Dana Vollmer set world records in the men's 100 breaststroke and women's 100 butterfly respectively, both erasing times set in 2009 before buoyancy-boosting polyurethane bodysuits were banned.
Van der Burgh became the first South African male to win individual Olympic swimming gold.
There was a further pool gold for France when top-ranked Camille Muffat won the women's 400 freestyle.
Phelps's silver in the relay was his first in these Games, which along with his 14 previous golds and two bronzes left him one shy of the all-time record of 18 medals held by Soviet gymnast Larisa Latynina.
The weather on Monday was cool and clear with only a 20 percent chance of rain - happy odds for Britons who have suffered one of their worst summers in years, including the wettest June in a century.
Less positive was news that Switzerland's Morganella was thrown out of the London Olympics for sending an offensive message on Twitter after his team's defeat by South Korea.
It follows the withdrawal last week, before the July 27-August 12 tournament got underway, of Greek triple jumper Paraskevi Papachristou for another tweet deemed racist.
By mid-afternoon on Monday, China had stretched its lead at the top of the medal rankings, with eight golds, four silvers and two bronzes eclipsing second-placed United States on three golds, five silvers and five bronzes.
The Chinese squad will also try to challenge the American favorites for the men's gymnastics team gold later on Monday.
Chinese swimmer Ye Shiwen became the first female swimmer to break a world record since the ban of high-tech suits on Saturday when she crushed her opponents in the women's 400 individual medley.
Arne Ljungqvist, International Olympic Committee medical chief, was asked by reporters whether her eye-popping swim had raised suspicions of doping.
"I say no," he replied. "Should a sudden raise in performance or a win be primarily suspect of being a cheat then sport is in danger because this ruins the charm of sport," said Ljungqvist, who has 40 years experience in anti-doping.
Later on Monday, the British men's hockey team faces off with Argentina, marking the latest twist in an intense sporting rivalry that stems from a brief war the two countries fought over the British-run Falkland Islands 30 years ago.
(Additional reporting by Karolos Grohmann, Michael Holden, Julian Linden; editing by Justin Palmer)