In the final moments of the Los Angeles marathon last weekend, the announcers were already narrating frontrunner Michael Kimani Kamau’s finish when Nathan Martin suddenly propelled forward, shocking newscasters and spectators.

The 36-year-old Martin prevailed in a single stride, stepping across the finish line an almost imperceptible fraction of a second before Kamau and becoming the first Black American to win the contest. He had challenged himself in the final miles of the race to keep putting his all into it, despite physical exhaustion, and finished the 26.2-mile race in 2 hours, 11 minutes and 18 seconds.

“It’s awesome to win, it’s awesome to get recognition, but it’s even better to push yourself and achieve whatever you can,” a fatigued Martin told reporter John W Davis after the race.

The finish was the closest in the 40-year history of the Los Angeles marathon, and a monumental achievement for Martin, a track and cross-country coach and substitute teacher at a high school in Michigan.

It came nearly three years after Martin became the fastest US-born Black marathoner, with an even quicker finish of 2 hours, 10 minutes and 45 seconds, at Grandma’s Marathon, an annual race in Duluth, Minnesota. But despite Martin’s impressive record, his last second win was a shock given Kamau’s lead.

Martin had stayed with a group of about five to six runners for much of the race, but took off from the group with about five miles remaining, pushing himself to move ahead, he told reporters.

Kamau, of Kenya, came into his line of sight roughly a mile and a half from the finish line, the Athletic reported, and in the final 100m experienced a “do-or-die” feeling that compelled him to push.

He was in the “hurt locker”, but dug deep, he told Davis.

“I always challenge myself to push, regardless to whether [there’s] somebody to chase or I’m all by myself because I wanna know I finished giving everything I had,” he said. “You can’t always win but you can always push.”

Martin crossed the finish line just before Kamau, who immediately collapsed to the ground. Commentators have noted that Kamau’s performance in the final 200m of the race was hampered after a spectator holding a flag stepped on the course, forcing him to veer, and then he appeared to follow a marathon motorcade in the wrong direction before reversing back the correct direction.

The Los Angeles marathon organization said in a statement that no protests of the win were filed and that the results of the race were unchanged.

“The vehicles made their planned exit 300m from the finish line at the intersection of Century Park West and Santa Monica Boulevard within sight of the finish line structure,” the organization said. “As with all major road racing events, our lead vehicles leave the course before approaching the finish line. Our vehicles did not make a wrong turn at this point or at any other during the event.”

The spectator’s behavior was cause for concern, the statement noted, adding that the organization will “review how future issues of this kind can be avoided as part of our post-race discussions”.

The organization continued: “Marathon road racing is a dynamic sport where pro athletes must combine endurance, tactical awareness and mental toughness to be successful. All of these elements were on display this weekend. We congratulate our podium finishers and all of our runners who participated in our event.”

Martin is only the second American man to win the Los Angeles marathon in three decades. Last year, Matt Richtman, 25, won the race, the first American to do so since Paul Pilkington’s victory in 1994.

Martin described the win as “surreal”.

“It’s amazing,” he told Davis. “You hope that you’re able to pull something off. It’s one of those things where you have to believe but until you manifest it, it’s just an idea.”

He ran in college and has spent years steadily improving his abilities. Martin has previously qualified for the US Olympic trials marathon.

The coach is committed to both running and his school, where cross-country season just began this week. He told Run last summer that because of coaching, he sometimes wouldn’t run until late in the evening.

“Don’t get me wrong, I enjoy pushing myself and testing and seeing what I can achieve, but the best days are when I’m able to help them out,” he said.

His coach said of the win: “Nathan led the [marathon] for a single stride today. The only step that mattered.”