New England Patriots quarterback Tom Brady says the side must forget the distraction of playing a regular-season game at Wembley on Sunday.
The Patriots face the St Louis Rams in the sixth International Series match.
"We're here to be ambassadors for the NFL and the players understand that," Brady told BBC London 94.9.
"But we realise our main goal is to win a football game. It will certainly be a much longer flight home if we don't take care of business."
The 35-year-old added: "I hope the event continues to grow and that's why we're here.
"The most important thing is using the next days to prepare and not get distracted by all the things you could possibly go out and do.
"It's not a vacation or a sight-seeing tour."
The Patriots, who made the Super Bowl in February, have started the season with four wins and three defeats.
"We're still growing as a team," Brady said.
"We're not even at the halfway point. Each step along the way, we've learnt and hopefully this weekend is the best game of the season.
"Our goals are still ahead of us and this will be a very important win for us, if we can get it, going into bye week next week.
"You look at this game as a very critical point and critical game in our season where if we can just get to 5-3, we feel like we're at a decent point where we've learned a lot form the last eight games."
This is the sixth year that an NFL match has been staged in London, but next season will see two games staged at Wembley.
The Jacksonville Jaguars will take on the San Francisco 49ers in October 2013, a month after the Minnesota Vikings meet the Pittsburgh Steelers.
Brady is unsure whether it is feasible to base a franchise outside of the United States permanently at this moment in time.
"I'm not sure," Brady added. "I don't make any of those decisions. If it was up to me, maybe one day if I was the owner of a team it would be.
"But I think it's a great thing that we're here.
"It's a great thing that people get to experience American Football and why I think we enjoy it so much. Whether it ever happens on a regular basis, those questions are probably for other people.
"But I know this experience is fun for us players and we look forward to the opportunity of sharing our game with people who probably don't get to see it very often.
"And maybe there are more games in the future. That, I think, would be the ultimate goal for everybody."