Four-time Olympic champion Michael Johnson crouched at the starting line, burst forward and ran down the track at the 80,000-seat stadium.
Never mind that Johnson was running for fun against local school kids, the track was just a temporary 60-meter strip of carpet and most of the stands were empty.
Exactly two years before the opening of the London Olympics, Johnson provided a glimpse Tuesday of what fans can look forward to come July 27, 2012.
"Obviously knowing that the Olympics are coming in two years' time, it's great to be here," said Johnson, a two-time 400-meter champion and gold medalist in the 200 and 4x400 relay. "Everything seems to be on time. The stadium looks great. It's going to be very exciting."
The starter for Johnson's race was Sebastian Coe, the former Olympic middle-distance great who heads London's organizing committee.
"It's just scintillating," Coe said. "Here's the greatest 400-meter runner the world has ever seen, and arguably the best 200-meter runner, and this is a guy that's running down a strip of tartan down the middle of your stadium two years out. It doesn't get any better."
Johnson wasn't the only athlete Tuesday to showcase London's Olympic venues as part of a series of activities across the city to mark the two-year countdown.
The spotlight was on the Olympic Park site in east London, where the external structures of the main venues are already complete and the arenas are set to be finished next year and ready to stage test events.
British cyclist Chris Hoy, who holds four Olympic gold medals, took a few spins around a temporary track inside the velodrome as construction workers wearing yellow hard hats cheered from the stands.
"You do imagine what it's going to be like when it's filled to the rafters, when it's the Olympic final," Hoy said. "You can sense that as soon as you walk in. It does get me really enthusiastic for it."
At the temporary basketball venue, where the floor still hasn't been installed, former NBA player John Amaechi shot a few hoops.
While the Olympic project is on track and on budget, organizers are under scrutiny as Britain's coalition government carries out $61 billion in public spending cuts to trim the record budget deficit.
The government recently ordered relatively modest cuts of $41 million in the budget of the Olympic Delivery Authority, the body responsible for building the venues. The overall construction and infrastructure budget stands at $14.3 billion.
The government has not ruled out further Olympic cuts.
Coe's separate privately financed organizing committee budget is $3 billion, raised from sponsorships, television fees, ticket sales and merchandising.
"We wake up every morning trying to figure out how we can deliver this in a more cost effective and efficient way," Coe said.
Earlier in the day, organizers launched a program to recruit 70,000 volunteers and urged people to apply for specialist positions such as doctors, anti-doping personnel and scoreboard operators. The sign-up for more general volunteer positions will open Sept. 15.
London Mayor Boris Johnson announced a separate program to recruit 8,000 "London Ambassadors." They will man key points across the city, such as railway stations and tourist spots, to help guide visitors around the capital.
"These will be the polite, courteous, smiling — without being irritating — faces of the city," Johnson said. "London will be the center of the greatest party on earth."
Tickets go on sale next year, and so far more than 1.4 million fans have registered. A total of 8 million tickets for the Olympics and 2 million for the Paralympics will be on sale.
"Now it's the public's turn," Coe said. "Don't wait. Start planning your games now."
The London 2012 committee opened its flagship merchandising store at St. Pancras International station in central London where, for the first time, soft toys of the child-friendly, one-eyed mascots Wenlock and Manderville went on sale at $38 apiece.
From St. Pancras, Olympic organizers, athletes and dignitaries took the Javelin bullet train for the six-minute journey to the Stratford International station at the Olympic Park.
The group toured the venues and walked across the new main bridge or "front door" to the Olympic Park for a firsthand look at progress on the square-mile site. A once-deprived industrial area of the capital is being transformed into a complex of venues and parkland that will be turned over to the public after the games.
Michael Johnson recalled the two-year countdown when he was training for the 1996 Atlanta Olympics, where he won the 200 and 400 and broke the 200 world record.
"There was just so much buzz and excitement from that point on," he said. "From two years out, for all of the athletes, this is certainly a motivation. It is reminding them what they're training for every day."
Johnson said the intimate nature of the Olympic stadium could be crucial.
"It's not about the stadium itself," he said. "It's about the crowd who come, and the spectators, and the energy that you get from those spectators. The more intimate a stadium is the more the athletes will feel that type of atmosphere."
Despite the overcast and muggy conditions Tuesday, Coe said he can imagine world records being set in the stadium in 2012.
"This is actually not a bad climate to be breaking world records in," he said. "This would be a perfect track and field day."
And how does he envisage the opening ceremony in the same place two years from now?
"I imagine lots of people in the crowd," he said, "and two or three people — particularly sitting around my seat — certainly being quite nervous."