NEW YORK — Geoffrey Mutai could train with some of the fastest marathoners in history.

Instead, he often chooses to run alone. That’s how the Kenyan star ensures he can hold steady, speedy splits without following someone else.

He used the skill to easily win the last two New York City Marathons. The race is a championship-style event, which means there is no pacemaker, a runner tasked with leading the pack to a certain time over the first half.

Pacemakers are vital to breaking world records. Wilson Kipsang set one at the Berlin Marathon just over a year ago on the flat course that’s perfect for lowering those marks, unlike the hilly route in New York.

This fall, though, Kipsang bypassed Berlin to make his NYC Marathon debut.

“It’s really cool because part of my dreams has been to run all the major races, to get the challenge and see what I can really do,” he said.

Kipsang did not meet the challenge of a championship-style event at the 2012 Olympics, when he built an early lead only to be passed and settle for a bronze medal.

With a pacemaker, Mutai explains, runners can “stay back and relax.” But on a championship-style course, “everyone is looking at you, and you look at each other.” All that jockeying for position is draining.

“You must use your energy from start to end and be prepared mentally,” said Mutai, Kipsang’s friend and occasional training partner.

Mutai is not only a skilled racer but blazing fast, too. In winning the 2011 Boston Marathon, another championship-style event, he ran the quickest 26.2 miles in history in 2 hours, 3 minutes, 2 seconds. That didn’t count as a world record because the course is considered too straight and downhill: For all the notoriety of Heartbreak Hill, the race has a net drop in elevation, and Mutai enjoyed a tailwind that day.

Kipsang’s world record was 2:03:23. Both of their marks fell five weeks ago, when another training partner, Dennis Kimetto, won Berlin in 2:02:57.

Mutai also shattered the course record in New York in 2011 with a 2:05:06 in near-perfect conditions. He seeks to become the first man to win three straight NYC Marathon titles since Alberto Salazar from 1980-82.

Sunday is forecast to be gusty, which isn’t conducive to another course record, though Mutai and Kipsang won’t rule it out.

But sometimes tactics make for much slower times than the capabilities of the contenders. That’s how Meb Keflezighi is a two-time major marathon champion even though his personal best, run in Boston this year, is more than 51/2 minutes slower than Mutai’s mark on the same course.

The American also won an Olympic silver medal in 2004. In 2009, he took the title in New York. Then this past April, Keflezighi ran what, considering the circumstances, will go down as one of the great marathons of all time.

In the first Boston Marathon since the 2013 bombings, the lead pack full of rivals with far faster personal bests plodded out to a slow pace. So Keflezighi decided to stick to his target splits. That meant breaking away, and when the pack finally tried to catch up, it was too late.

Keflezighi was the first American man to win Boston in more than three decades, transforming a finish line that was a site of horror a year earlier into a scene of joy.

Bob Larsen, his coach since his UCLA days, said Keflezighi benefited from running track, where competitors must make split-second decisions. Many top marathoners today went straight into road racing. That experience has served Keflezighi well in the final miles when all the oxygen is going to a runner’s legs.

“Other people start making mistakes because there isn’t the oxygen going to their brain, and you get lazy in your thinking; you get a little bit sluggish,” Larsen said. “And he stays sharp and makes great decisions.”

The men’s field brims with other contenders with success in championship-style races. Ethiopia’s Lelisa Desisa is the 2013 Boston Marathon champ. Uganda’s Stephen Kiprotich won the 2012 Olympic gold medal and 2013 world title.

About 50,000 runners are expected to start the 44th edition of the NYC Marathon.

On the women’s side, two of the favorites have sour memories of race tactics gone awry in New York. Kenya’s Mary Keitany sped out to a big lead in 2011 only to be caught by Ethiopians Firehiwot Dado and Buzunesh Deba. In the next NYC Marathon, Deba was the one surging ahead, and she too was overtaken, settling for her second straight runner-up finish. The Bronx resident is seeking to finally top the podium Sunday and become the first New Yorker in 40 years to win the race.

Priscah Jeptoo, who chased down Deba, won’t defend her title because of a leg injury. Dado is back this year, as is 2010 winner Edna Kiplagat of Kenya.

Keflezighi knows that if Mutai and Kipsang challenge the course record Sunday, he doesn’t have a shot. And that’s OK.

“If they’re going to go from the get-go, you know what? I have no business going with that,” he said.

“When I did what I did in Boston, I wasn’t doing something crazy. I just did what was common sense.”