Sisay Lemma of Ethiopia set a blistering pace and held on to win the Boston Marathon on Monday, running alone through most of the course to finish in 2 hours, 6 minutes, 17 seconds — the 10th-fastest time in the race’s 128-year history.

The 2021 London champion, Lemma arrived in Boston with the fastest time in the field, becoming just the fourth person ever to break 2:02:00 when he won in Valencia last year. And he showed it on the course, separating himself from the pack in the first 3 miles and opening a lead of more than half of a mile.

Lemma ran the first half in 60:19 — 99 seconds faster than Geoffrey Mutai’s course-record pace in 2011, when he finished in 2:03:02 — the fastest marathon in history to that point. Fellow Ethiopian Mohamed Esa closed the gap through the last few miles, finishing second by 41 seconds; two-time defending champion Evans Chebet was third.

“I decided that I wanted to start fast early,” said Lemma, whose victory in London in 2021 was his only other major marathon victory. “I kept the pace and I won.”

The town of Hopkinton celebrated its 100th anniversary as the starting line for the Boston Marathon, sending off a field of 17 former champions and nearly 30,000 other runners. Near the finish on Boylston Street 26.2 miles away, officials observed the anniversary of the 2013 bombing that killed three and wounded hundreds more.

Sunny skies and minimal wind greeted the runners, with temperatures that rose into the 60s in late morning. As the field went through Natick, the fourth of eight cities and towns on the route, athletes splashed water on themselves to cool off.