The biggest test yet of whether the Olympic Park is ready for the London 2012 Games begins today.
With six major sporting events and 11,000 staff, the east London venue in Stratford is getting its most comprehensive operational workout to date.
From May 2 to 8, five venues will stage three Olympic and three Paralympic sports.
More than 140,000 spectators will watch 3,000 athletes take part in hockey, wheelchair tennis, water polo, athletics, boccia and Paralympic athletics.
London 2012's sport director Debbie Jevans said: "The coming days are the big final test of our Olympic Park operations and sporting venues and also our workforce, who have been excellent throughout all of the events."
These fixtures make up the last of 42 test events at 28 venues in the past 12 months which London 2012 organisers are billing as "one of the most comprehensive testing programmes" for a Games.
At peak times more than 60 pedestrian screening areas at Stratford Gate and 15 at Greenway Gate will allow access for a minimum of 4,000 spectators to enter the Park each day, peaking at about 75,000 on May 5.
The Olympic Stadium will host the BUCS Visa Outdoor Athletics Championships and the Visa London Disability Grand Prix. More than 40,000 spectators are expected on the evening of May 5 for the "2012 hours to go" event when the stadium is to be officially opened by a member of the audience.
The Riverbank Arena, Eton Manor and the Water Polo Arena will host their first sporting competitions.
These include the Visa International Invitational Hockey Tournament, Eton Manor Wheelchair Tennis International and Visa Water Polo International.
The workings of the field of play, equipment, results, scoring and timing systems plus training of the workforce will come under the spotlight.
Field of play testing will also take place at the London Boccia Invitational 2012 where players' friends and families will make up some of the crowd.
The final day of the Sainsbury's 2012 School Games, involving 1,600 elite school-aged athletes will also be held in the Park in front of around 35,000 spectators.
Outside of the Olympic Park, the London Para Archery International Tournament at the Royal Artillery Barracks will run from May 3 to 6.
London 2012 chairman Lord Coe said: "Testing the Olympic Park and its operations is a hugely important part of our plans.
"Over the last 10 months, over 250,000 spectators have watched world-class sport as part of the London Prepares series test event programme, and, in doing so, every one of them is helping us deliver the best possible Games this summer."