Mo Farah says he had to "dig in deep" after winning a record sixth successive
The Olympic champion, 36, finished the race with a personal best time of 59 minutes and seven seconds.
, he ran back along the course to celebrate the victory with fans.
Farah told BBC Sport the race was good preparation for the Chicago Marathon on October 13.
"The crowd was so loud I didn't know if he was closing the gap so I kept looking behind," he said.
"I've really enjoyed it but the past couple of years has been in the middle of marathon preparation.
"It was good to test myself. Things are looking good and I'm happy with the win.
"Tokyo is definitely on the cards - as an athlete you always want to represent your country.
"You just have to take it one year at a time. Hopefully, come Tokyo time, we will be in the mix."
Tamirat Tola, seven seconds behind Farah, crossed the line 42 seconds ahead of Holland's third-placed Abdi Nageeye, with Britain's Callum Hawkins coming home fourth in one hour and 39 seconds.
In the women's elite race, Kenya's Brigid Kosgei set a new course record and and broke the world half marathon record by finishing in a time of one hour, four minutes and 28 seconds.
David Weir took the wheelchair race for an eighth time. Jade Jones-Hall sealed a British double in the women's race.
