When 51 two-man teams step off the starting line at this year's Best Ranger Competition, it could be the last time the famously tough event is men-only.

Competitors must be graduates of the Army Ranger School, which until this month has been open only to men.

The Army on April 20 will conduct an integrated assessment at the storied Ranger School as part of a wider effort to determine how to open combat arms jobs to women. So far, 12 women have qualified to attend the two-month course.

As part of the assessment, women who successfully complete Ranger School will receive a certificate and be awarded the coveted Ranger tab. They will not, however, be assigned to the 75th Ranger Regiment, which is separate from Ranger School.

"If a woman earns the Ranger tab prior to the Best Ranger Competition 2016, she is eligible to compete in BRC 2016 or any subsequent BRCs," said Gary Jones, a spokesman for Fort Benning, Georgia.

The 2015 David E. Grange Jr. Best Ranger Competition kicks off Friday at Fort Benning. The three-day competition pits two-man teams against each other in back-to-back events, with the winning duo earning the title of Best Ranger.

The competition, hosted by the Airborne and Ranger Training Brigade, tests competitors on their physical conditioning, Ranger skills and team strategies. The competition events are back-to-back and around the clock for 60 hours, allowing little time for rest and meals.

In the past, events included weapons firing, extended road marches, day and night land navigation courses, Ranger skills and parachute jumps. All events are timed, and competitors score points for each completed event. Both team members must complete each task.

The Best Ranger Competition was established in 1982 and has been compared to Ironman and Eco-Challenge competitions.

Last year, only 26 of the 50 teams to begin the competition made it into the final day. Of the 50 teams at the starting line in 2013, only 23 finished the competition. And in 2012, 34 of the 50 teams completed the competition.

This year's competition will begin at 6 a.m. on Friday; organizers estimate the competition will wrap up about 4 p.m. Sunday.

A formal awards ceremony is scheduled for 10 a.m. April 13 at McGinnis-Wickam Hall in Fort Benning's Marshall Auditorium.

The competition is open to the public. A schedule of events will be released to the public on Wednesday on the Fort Benning Facebook page. Family, friends and spectators are encouraged to tweet updates on their teams during the competition using the hashtag #2015Best Ranger, @Fort Benning.