Meb Keflezighi looks to become the oldest U.S. Olympic runner but will be challenged by a deep field for three Olympic team spots.

The U.S. Olympic Marathon Trials will be held in Los Angeles on Feb. 13, where the top three men and women across the finish line will qualify to represent the United States at the 2016 Olympics in Rio de Janeiro.

Whatever happens on the streets of L.A., his year’s men’s team will have a much different look than that of 2012, as runner-up Ryan Hall, the fastest American ever over 26.2 miles, has retired and third-place finisher Abdi Abdirahman has withdrawn due to injury.

The 2012 trials winner, Meb Keflezighi, looks to make history and his fourth U.S. Olympic team but he will be challenged by a field of very talented competitors.

Here’s a look at how the field stacks up:

The favorites

Meb Keflezighi – Personal best: 2:08:37 (2014 Boston Marathon)

The 40-year old hopes to become the oldest U.S. Olympic runner in history as he looks to repeat as the trials champion. In 2012, he won the race in 2:09:08 and went on to finish fourth in London.

After the Olympics, Keflezighi struggled to stay healthy, battling a series of injuries. He placed 23rd at the 2013 New York City Marathon in a career-worst time of 2:23:47. He silenced retirement suggestions by winning the 2014 Boston Marathon in a personal best, just one year after twin bombings claimed the lives of three and injured more than 130 others.

His victory in Boston made Meb the biggest star in American distance running and he fared well at the 2014 New York City Marathon placing fourth in 2:13:18. In his title defense at the 2015 Boston Marathon, Keflezighi led in the early half of the race before finishing eighth, and second overall among Americans. His finishing time of 2:12:42 was a U.S. record for an athlete over 40 years old.

In his most recent race, Keflezighi was seventh at the 2015 New York City Marathon, but the top American. His agent tells SI, there have been no major hiccups in the training leading up to the Olympic Trials.

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Galen Rupp – Personal best: NA (Marathon debut)

Rupp has an Olympic silver medal on his résumé from the 10,000 meters at the 2012 Olympics and is arguably the most accomplished U.S. distance runner of his generation. His marathon debut has been eagerly awaited. While he may not have the experience over 26.2 miles, he most definitely has the talent to run with the leaders in a tactical race.

Rupp qualified for the trials with a 1:01:20 half-marathon on Dec. 13 in Portland, Ore. The time is slower than his personal best of 1:00:30 from the 2011 NYC Half but was still the second-fastest U.S. mark of 2015.

Last year on the track, Rupp won his seventh U.S. title at 10,000 meters and went on to finish fifth at the world championships in Beijing. He also finished fifth at 5,000 meters as he has not won a medal at a global championship since London.​

Rupp has said that if he finishes in the top three in Los Angeles, he will still run the 5,000 and 10,000 on the track at the U.S. Olympic Trials in July. If he finishes in the top three in those two events, he would then be faced with choosing which two races to run in Rio. If he scraps the marathon in favor of the two track races, then Saturday’s fourth-place finisher would be upgraded to the Olympic team.

The former Oregon Duck star was mentioned in a joint BBC and ProPublica report that alleged Nike Oregon Project coach Alberto Salazar pushed the boundaries on doping rules to gain a competitive advantage by encouraging the use of prescription medication and therapeutic use exemptions. Rupp has been coached by Salazar since he was a teenager and has never tested positive for any performance enhancing drugs. Salazar remains under investigation by the U.S. Anti-Doping Agency. Salazar and Rupp have denied all allegations.

Did you know? Keflezighi and Rupp have only faced off three times in their career—twice on the track, once on the roads. Rupp has won all three match-ups. Most recent: 2011 NYC Half, Rupp 3rd overall; Keflezighi 15th.

The Contenders

Pat Greenhouse/The Boston Globe via Getty Images

Dathan Ritzenhein – Personal best: 2:07:47 (2012 Chicago Marathon)

Despite being in “the best shape of his life” according to his coach at the time, Alberto Salazar, and race commentators, a PR performance of 2:09:55 was not enough for him to catch Abdi Abdirahman for the third spot on the U.S. Olympic team. Ritzenhein finished fourth but later went on to make the Olympic team in the 10,000 meters.

His next crack at the marathon distance was a personal best of 2:07:47 at the 2012 Chicago Marathon, where he finished as the top American but ninth overall. The time also made him the third-fastest American of all-time, behind Hall and Khalid Khannouchi. Ritz improved to fifth place the following year but ran 2:09:45, which is still among the fastest by an American in the last four years.

Injuries plagued Ritzenhein in 2014 to the point that he only raced a 10-miler in August. In his return to the marathon distance at the 2015 Boston Marathon, Ritzenhein beat Keflezighi and placed 7th overall in 2:11:20. In the four U.S. championship races that he ran in 2015, he finished on the podium each time.

Injuries struck again in the build up for the 2016 trials, as Ritzenhein reported hip bursitis in November. He later told Carrie Tollefson’s web show that he was feeling healthy and prepared for Los Angeles.

• 2012 U.S. Olympic Marathon team, four years later​

Luke Puskedra – Personal best: 2:10:24 (2015 Chicago Marathon)

While many of the top U.S. marathoners rested during the fall to prepare for Trials, Puskedra used the 2015 Chicago Marathon to rebound from a terrible marathon debut in New York City the previous fall, where he ran 2:28:54 (a time slower than the winner of the women’s race).

The former Oregon Duck was open about quitting running after leaving Salazar and the Nike Oregon Project before running Grandma’s Marathon in Duluth, Minn., in the summer. He lowered his personal best to 2:15.26 before his big break-out in the Windy City. Puskedra, who is tall for a marathoner at 6'3", raised eyebrows with a 2:10:24 run.

He entered the Olympic conversation and backed it up running a personal best 1:01:29 for fourth place at the Houston Half-Marathon on Jan. 17.

Elkanah Kibet – Personal best: 2:11.31 (2015 Chicago Marathon)

A lot was unknown about Kibet before his marathon debut in Chicago last October. He attended Auburn before enlisting in the U.S. Army and becoming an American citizen in Aug. 2015.

In the race, Kibet took off from the lead pack of East Africans trying to win the race wire-to-wire before eventually being reeled in and finishing seventh overall. Puskedra was the only American ahead of him.

Did you know? As a member of the U.S. Army, Kibet had to run very early in the mornings or late at night to avoid the crazy temperatures over 100 degrees in Kuwait. (Via LetsRun.com)

Jared Ward – Personal best: 2:12:56 (2015 L.A. Marathon)

Ward debuted in the marathon at Chicago in 2013, in the middle of his senior year of cross-country while his eligibility was up in the air due to an odd rule regarding his participation in a fun run. He finished his collegiate career and dedicated himself to the roads. Much like Puskedra, he has made a steady progression over 26.2 miles. He debuted at 2:16:17, dropped to 2:14:00 in 2014 and then claimed the U.S. championship in Los Angeles last March in 2:12:56. He did not race a fall marathon in 2015. Ward is coached by two-time Olympic marathoner Ed Eyestone.

Bobby Curtis – Personal best: 2:11:20 (2014 Chicago Marathon)

Curtis is the 2008 NCAA champion at 5,000-meters and holds a personal best of 27:24.67​ for 10,000-meters. Since debuting at the marathon distance with a 2:16:44 at the 2011 New York City Marathon, he has developed well under the direction of the Brooks Hanson-Distance Project. He did not contest the 2012 U.S. Olympic Marathon trials and finished 10th for the 10,000-meters on the track. His best performance, and most recent, over 26.2 miles was a top American finish at the 2014 Chicago Marathon, where he ran a personal best of 2:11:20​.

The debutants

Diego Estrada – Personal best: NA

Estrada ran the fastest U.S. half-marathon of 2015 with his 1:00:51 performance at the 2015 U.S. championships in Houston. He pulled away from the pack early and never relinquished the lead. Estrada has been that type of racer his entire career—but that may not be the wisest of strategies as he makes his marathon debut.

When he made his decision to run the marathon trials, he told SI, “My goal is to get to 20 miles and take it from there. Time is not really a factor so I just want to finish it and go under 2:15.”

That time may not be enough to make the Olympic team but would be an encouraging start to his career at 26.2 miles.

Estrada competed in the 10,000 meters at the 2012 London Games and finished 21st for Mexico.

Michael Dodge/Getty Images

Sam Chelanga – Personal best: NA

A battle between Chelanga and Rupp would bring back memories of their duels in college. Chelanga has a half-marathon personal best of 1:01:04, run before he became an American citizen last August. Chelanga may not have experience at 26.2 miles but has spent the last few months training with 2012 Olympian Abdi Abdirahman, who has made four Olympic teams.

On the bubble

All it takes is one great race to make the U.S. Olympic team. The following runners have personal bests that put them in the conversation, if they can put together that great race.

Nick Arciniaga (2:11:30); Jeff Eggleston (2:10:52); Matt Llano (2:12:28); Fernando Cabada (2:11:36) and Tyler Pennel (2:13:32)

The race will be broadcast live on NBC from 1 p.m. to 4 p.m. ET. I will be on-site providing live updates from @ChrisChavezSI on Twitter.