Great Britain's Mo Farah beat out his former training partner and defending champion Galen Rupp to win the 2018 Bank of America Chicago Marathon Sunday.

In only his third marathon and his first 42K on U.S. soil, Farah went head-to-head with a tight field of elite athletes, taking the lead with a huge breakaway in the final mile against fellow Chicago newcomer Mosinet Geremew. 

"It was nice to be able to race against Galen and the rest of the guys," Farah said after the race. "He won last year here and it was nice to be able to come back the following year and win." 

Farah and Rupp, who last year became the first American man to win the Bank of America Chicago Marathon in more than a decade, made history together in the 2012 London Olympics, finishing with gold and silver medals in the 10,000m.

I’m happy for Mo to win. He ran unbelievable," Rupp said after the race. "It was a good day for our team and, yeah, I ran as hard as I could at the end of the day I’m not going to look back with any regrets." 

Farah made headlines in the 2016 Rio Olympics when he experienced a dramatic fall, but regained his footing and ultimately won his second straight gold.

"It was amazing to cross the line first. This is a major marathon," he said Sunday.