To promote American football in the UK, the NFL plays a high profile match internationally to widen interest in the sport overseas.
The rally was attended by over 38,000 people who came to see the 2010 Pepsi Max NFL International Series hosted by the San Francisco 49ers ahead of their game with rival team the Denver Broncos.
Flawless performed on stage alongside The Cuban Brothers and American rapper Asher Roth.
“I was absolutely thrilled that tens of thousands of NFL fans came out to Trafalgar Square today,” said Alistair Kirkwood, managing director, NFL UK.”
Photo gallery: Flawless at the NFL UK pep rally 2010
Click thumbnails to see large photos
All photos courtest of NFL UK/Sean Ryan.