So far, more than 400 runners have qualified for the Olympic Trials Marathon, which will take place Feb. 13 in Los Angeles. If any more are going to get in, it will have to be this weekend.

The cut-off for the qualifying window is Sunday, which means this weekend’s races have added meaning for runners still trying to nab the qualifying standard. For men, the “B” standard is a 2:19:00 marathon time or a 1:05:00 half marathon. For women, the “B” standard is a 2:45:00 marathon or a 1:15:00 half marathon.

Here’s a look at some of the races taking place this weekend that could have an impact on the Olympic Trials marathon field next month:

Rock ‘n’ Roll Arizona Marathon and 1/2

Rock ‘n’ Roll Arizona is boasting a fast half-marathon field in both the men’s and women’s races, which could help several runners looking to get under the qualifying standard.

In all, 10 women running the half marathon have already met the 1:15 Olympic Trials standard, which could benefit several other elites looking to join them. On the men’s side, four-time Olympian Abdi Abdirhman is pacing at 1:04:45 in hopes of helping a few more elite men into the Trials.

“My goal is to run hard, run solid and help as many people get across that line under 65 minutes,” Abdirhman said.

RELATED: Abdirhman Leading the Way for Olympic Hopefuls at Rock ‘n’ Roll Arizona

Houston Marathon

The race that hosted the 2012 Olympic Trials marathon will this year serve as either a tune-up or a last-chance qualifier for many elites.

The half marathon field will have several qualifiers tuning up, including Diego Estrada, Jeffrey Eggleston, Craig Leon and Luke Puskedra in the men’s race and Sara Hall, Serena Burla, Jen Rhines and Colleen De Reuck in the women’s race.

In the marathon, one of those looking for a Trials-qualifying time is Sage Canaday, an elite ultrarunner who ran the Trials marathon in both 2008 and 2012 and is looking to keep his streak going. His time of 2:19:12 in tough conditions at the Boston Marathon last April barely missed the standard, and he’ll make one more go of it in Texas.

Naples Daily News Half Marathon

Race director Perry Silverman saw the NDN Half Marathon’s flat course, ideal weather and last-chance Trials qualifying date as a perfect opportunity to pull out the red carpet for competitive runners. Last March he announced that 25 men and 25 women trying to qualify for the Trials would get complimentary housing from Gulf Coast Runners members, as well as a $100 travel stipend, an elite entry and a chance at a $10,000 American-only prize purse.

Carlsbad Marathon and Half Marathon

The picturesque race in north San Diego County runs along the Pacific coast, with gently rolling terrain and no major hills. Several women broke 1:15 last year in the half marathon.