The window to register for the 2018 TCS New York City Marathon is closing, so if you haven’t committed to run this year, this week is your last chance.

Registration for the race on Nov. 4, 2018, opened on Jan. 15 and will close at 11:59 a.m. Thursday, Feb. 15, online at tcsnycmarathon.org.

For a guaranteed spot, eligible runners must have hit the New York Road Runners (NYRR) time-qualifier, which is based on age, in a previous race. For example, a male runner who is between the ages of 18 and 34 must have hit at least 2 hours and 53 minutes in a NYRR marathon and 1 hour and 21 minutes in a half-marathon. A female runner of the same age must have run a NYRR marathon in 3 hours and 13 minutes and a half-marathon in 1 hour and 32 minutes, according to the NYRR website.

If you aren’t a time-qualified runner, you can enter into a drawing before Thursday that will take place on Feb. 28. It doesn’t guarantee a spot but helps “preserve the geographic diversity of the race,” and is open to NYC metro area applicants, those outside of the metro area and international applicants.

Check the marathon’s website for other ways to enter.

The race, which saw 50,773 runners last year, was the largest marathon in the world in 2017, according to the NYRR.

Its route spans all five boroughs — starting in Staten Island, then heading through parts of Brooklyn, Queens, the Bronx and Manhattan, finishing in Central Park.

Last year, Shalane Flanagan became the first American woman in 40 years and the first American since 2009 to win the women’s marathon in 2 hours, 26 minutes and 53 seconds.

Maybe you’ll be the next — just make sure you register on time.