America's First Lady Michelle Obama gave her own personal good luck message to Team USA at a breakfast before Friday night's opening ceremony.
Obama urged America's athletes to "have fun, breathe a bit, but also win", as she met them at their training base in east London.
The First Lady is leading the US presidential delegation which includes a ringside seat at tonight's ceremony.
She began her trip to the capital with a visit to the University of East London (UEL), Team USA's home during the Games, and will also take part in a Let's Move! event, as well as joining a reception at Buckingham Palace.
"I can't believe I am here, I am beyond proud. Thank you so much, it's a pleasure and a joy and an honour for me to be here with all of you. I can't begin to tell you how amazing it is for me to be leading the delegation."
Obama explained how, as a child, she was "just in awe of these athletes and my family, we would sit together for hours watching these men and women perform feats of endurance, speed and grace that would have us cheering at the top of our lungs."
She said she and her brother hoped that they would one day achieve something "just as great" for themselves.
Obama continued: "I am still so inspired by all of you.
"We are all proud of you all, we really are.
"You have got a country back home who is rooting for you every single second, so you have already won."
Obama also told the athletes the Olympics were particularly special to her family because of her father's battle with multiple sclerosis.
"My father contracted MS in the prime of his life," she said, describing how in a matter of years he went from a "thriving competitor" to being unable to walk.
"But he retained the love of sports, and the Olympics was a special time for him."
After her speech, Mrs Obama met the athletes, posing for photographs, before leaving for a Let's Move! sporting event at the US Ambassador's residence in central London for about 1,000 US military children plus US and British students.
US First Lady Michelle Obama (C) poses w
US First Lady Michelle Obama (C) poses with members of the US Olympic team as she visits their Olympic base in east London on July 27, 2012 ahead of the London 2012 Olympic Games. AFP PHOTO/CARL COURT (Photo credit should read CARL COURT/AFP/GettyImages)