The NFL is helping to fund Tottenham Hotspur's new stadium and has contributed £10 million ($12.8m) to the project so far, sources have told ESPN FC.
The initial payment, recorded in the club's financial results, will go towards the tailoring of the 61,000-seater stadium for the hosting of NFL matches.
It is the first part of a significant contribution from the NFL to the overall cost of Spurs' new home, which it is estimated will be around £800m.
Tottenham have agreed a 10-year deal for the NFL to host a minimum of two matches per year at the stadium, which is expected to open for the start of the 2018-19 season.
The NFL will also pay the club a set fee every time it uses the venue.
The new stadium will include a retractable synthetic surface, set beneath the grass pitch, that will be used for NFL games.
Spurs will use the artificial surface for events including concerts, and the sources said the NFL would therefore not foot the entire bill for it.
The organisation will, however, pay for other features including four NFL-sized locker rooms and additional medical and media suites.
Speaking last year, Spurs chairman Daniel Levy told ESPN: "If it ever got to a stage where the NFL decided it wanted to have a permanent team in London, this stadium could literally be their stadium as opposed to an NFL team feeling they're renting Tottenham's stadium."
Mark Waller, the NFL executive vice-president who is working with Levy on the project, has said the NFL hopes to have a permanent franchise in London by 2020.
Last month, Tottenham director Donna-Maria Cullen revealed that the cost of the new stadium, adjacent to White Hart Lane, had nearly doubled from the original £400m estimate, partly down to the weakening of the pound after Britain's vote to leave the European Union.