The last remaining female soldier in training at the U.S. Army’s Ranger School has advanced to its third and final phase, Army officials said Friday, leaving open the possibility that the school could graduate a third woman from the first class to ever include women.

The woman passed the course’s trying Mountain Phase in the Chattahoochee National Forest in northern Georgia on her second attempt. She was one of three female soldiers left this summer in training in the first Ranger School class to ever include female soldiers, but fell behind the other two in July when they passed mountaineering training on the first try.

Those women — Capt. Kristen Griest, a military police officer, and 1st Lt. Shaye Haver, an Apache helicopter pilot — went on last week to become the first female graduates ever of Ranger School, a grueling course that is considered the Army’s premier school for training leaders who serve in combat. The Army opened it for the first time in April to 20 women as it carries out research required by the Pentagon’s landmark 2013 decision to open all jobs in the military to female service members.

The remaining woman, who has not been identified while she is in training by the Army or media, advanced to the third phase in the swamps and streams in and around Eglin Air Force Base in Florida with 103 men, Army officials said. Like Griest and Haver, she is a graduate of the U.S. Military Academy at West Point, N.Y.

An additional 45 men were “recycled” and will be given another attempt to complete the Mountain Phase, and 16 men were dropped from the course entirely. Recycling is a common part of Ranger School, and granted to many students who complete some aspects of training in a phase, but fall short in something specific.

The graduation of Griest and Haver has put new pressure on the U.S. military to make women eligible to service across all combat ranks. Thus far, the service has said that it would allow any female Ranger School graduate to wear its prestigious Ranger Tab, but it has kept closed the elite 75th Ranger Regiment, an all-male light-infantry force that conducts raids and other Special Operations.

The Mountain Phase includes mountaineering lessons, a knot test, an exhausting foot march up Mount Yonah near Cleveland, Ga., and 10 days of simulated combat patrols in which students take turns leading fellow soldiers, and are occasionally ambushed in the process. Those who advanced are transported by aircraft to Eglin Air Force Base and the Ranger outpost on it, Camp James E. Rudder.

The remaining woman and her male counterparts could graduate from Ranger School as soon as Sept. 18 if they complete the third major part of Ranger School — Florida Phase — on the first try. The graduation ceremonies are held at Fort Benning, Ga., where the Airborne and Ranger Training Brigade that oversees the school has headquarters.

Ranger School first opened to women April 20, after 108 women attempted a pre-Ranger School course at Fort Benning that the service required. Twenty women passed it, and 19 opted to attempt tackle Ranger School. They were joined by 380 men.

Griest, Haver, the third woman still in training and five other female soldiers completed an initial physical fitness test at Ranger School, but twice fell short of completing the first phase of training. Griest, Haver and the remaining female soldier were then offered a “Day 1” recycle, in which they can continue training, but only if they start over from the beginning.

All three remaining women advanced to the Mountain Phase this summer, and Griest and Haver completed it and the following Florida Phase on their first try.