Meb Kefelzighi became the first American man to win the Boston Marathon since 1983 yesterday, and he did it with some unexpected help from his countrymen.

According to Robert Johnson of LetsRun.com, a group of elite American runners led by Ryan Hall intentionally kept the pace slow midway through the race so Meb had a chance to win.

Here's how it worked.

Meb and one other runner broke away from the pack early in the race at the 15k mark. All of the elite African runners were way behind (1 minute, 21 seconds, at one point) halfway through the race.

Meb, at age 38, wasn't considered a real top-tier contender before the race, so the Africans were keeping a slow pace and saving their energy for the end of the race, when Meb would inevitably fall back to the pack.

Around the midpoint Hall and a group of American runners caught up to the Africans. The Americans could have maintained their pace and passed the Africans — a move that would have quickened the pace and cut into Meb's lead. Instead, Hall told everyone to slow down so they wouldn't catch Meb.

Runner Nick Arciniaga told Let's Run:

"I was in the lead pack with all of the other Americans and all of the Africans and about 15k to 20k, Ryan Hall and I were running side by side, in front of the lead pack but not really pushing it, and Ryan just kept turning over to me, talking (to me and saying), ‘Hey don’t push the pace. If [the Africans] want to let [Meb] go, they are going to have work to catch back up to [him]. We are not going to help them out with that at all. If we want an American to win, this is how it’s going to be done.’

The Americans never picked up the pace, and by the time the Africans broke away to catch Meb by themselves, it was too late.

It's a selfless move by Hall. He and Meb have long been the two best American distance runners. In 2010 The New York Times wrote a story about their "friendly rivalry," and it mentioned how important it was to them for an American to win the Boston Marathon.

Hall, who finished 20th, could have taken off and tried to catch Meb himself. Instead he organized other runners in a strategy that grew Meb's lead.

The American won by just 11 seconds.