Walking down my road this week I spied a group of 30 beautiful women in matching blue lycra uniforms bundling into a minivan.
This was not a sight I expected to see on a West London street. It was like I'd walked into a Hollywood movie.
My mind raced. Who were these perfectly-formed ladies speaking in American?
I've had a while to think about it and I'm almost certain they were cheerleaders. It seems the most rational explanation as on Sunday evening the Jacksonville Jaguars play the San Francisco 49ers in the International Series at Wembley Stadium.
Whether NFL cheerleaders are staying on my road is up for debate. But there is no denying that American Football has arrived in London in a big way.
Despite a busy fixture list of Premier League football – or soccer, whatever you say – most English sports fans know there is a NFL game being played on the weekend.
NFL banners flutter above Regent Street and if you walk around central London you are sure to bump into an excited 49ers or Jaguars fan.
Americans in London are hardly rare but what is interesting is that these American Football fans are not American, they are European.
While the NFL has been popular in Europe since the 1980s, Wembley started entertaining America's biggest and bulkiest stars in 2007.
I spoke to Norwegian 49er fans Sebastian and Eric who were staying in Knightsbridge ahead of the main event.
|'Big' Ben Roethlisberger played for Pittsburgh against Minnesota in London last month [AP]
"I really liked the San Francisco 49ers when I first started watching the game four years ago, I fell in love with them," says 20-year-old Eric.
"We've travelled to London to see the game. It's a bit cheaper and easier than the trip to San Francisco. I might have to save for that!".
Sebastian made the trip to London to join in the fun but he can also see the more serious side.
"It's good publicity for the NFL to play a game in Europe. We have two other 49er fans in our hotel from Switzerland. There are many fans from Europe around as it's cheap to get to London and a good opportunity to see a different sport in a huge venue like Wembley."
But what about English sports fans? How do they feel about NFL arriving on their doorstep?
Al Jazeera English's production crew certainly don't have any complaints. Six are taking part in a fierce NFL fantasy football league. They have even created their own table which they have pinned to the wall in the director's control room.
"There is a fanbase of more than one million in the UK and then there's the rest of Europe," says camera supervisior Craig Mellors, who is being named and shamed for his woeful display in fantasy football.
"I support the Chicago Bears and went to see them play in 2011. I have always followed the game but it's expensive to get a ticket to Wembley."
Despite tickets costing over $100, Wembley has not struggled to get bums on seats. Anything but.
The 2013 fixtures sold out in two days, nine months in advance (the Pittsburgh Steelers played the Minnesota Vikings last month). On-going popularity for the Series has seen the Jacksonville Jaguars sign a contract from 2013-2016, and in 2014 there will be three games played at Wembley for the first time.
NFL's London future is looking bright – so bright that rumours are still bubbling about a team setting up camp in the capital permanently.
While speaking to Al Jazeera English sports correspondent Lee Wellings this week, Jacksonville Jaguars owner Shahid Khan did not close the door on this possibility.
"I don’t think you can rule anything out or in. This is an exploratory experimental phase to see what fans want and what the league can provide," said Khan.
It's a totally different experience to watching a soccer match at Wembley. I think we have space for both.
It is perhaps only fair American Football gets a taste of London after the rise of soccer in the United States.
"NFL is really big in the States – and now we are exporting our product to the UK. It is a good thing," American sports fan Ron Ringer tells me.
"Soccer was not a big part of the USA but now it is. Beckham was principally responsible for soccer growing and becoming popular. There are more juvenile leagues now.
"What seems to be happening is a cultural exchange between the U.S. and the United Kingdom."
Ron has put his finger on it. And this transatlantic football exchange shows no signs of waning.
In fact, with four American NFL owners running Premier League clubs (Fulham, Manchester United, Aston Villa and Arsenal) things are likely to get more integrated.
But is there space for another brand of football, with the Premier League so strong in the UK?
"It's not just about the sport, it is about American culture. Americans do things big and they know how to party. NFL games are just one long celebration," English Jaguars fan Sarah Knight tells me.
"It's a totally different experience to watching a soccer match at Wembley. I think we have space for both."
It could be a while before a NFL team sets up camp in the UK but signs are showing that demand for American Football has never been higher. And if that means more cheerleaders on the streets, very few sports fans – male ones at least – will be complaining.