PHILADELPHIA -- The Washington Redskins lost another quarterback. They lost another game, too. And a season that started to look promising a month ago now appears headed for a tough finish.

Redskins quarterback Colt McCoy broke his right fibula Monday in a 28-13 loss to the Philadelphia Eagles, ending his season in only his second start this year. He's also the second Redskins starting quarterback to suffer such a fate. Alex Smith broke his fibula and tibia in Week 11.

"This is a tough blow," Redskins coach Jay Gruden said. "Losing Alex was one thing. He was a great leader, great quarterback. Then Colt finally gets his opportunity and he gets kicked in the leg and breaks it. I'm heartbroken for both of those guys."

That means the 6-6 Redskins must try to stay in the playoff race with Mark Sanchez, who was signed on Nov. 19 and replaced McCoy on Monday. The Redskins now have a 23.8 percent chance to make the playoffs, according to ESPN's Football Power Index. They're tied with Philadelphia for second in the NFC East, a game behind Dallas.

They'll also have to sign another quarterback to back up McCoy. Two weeks ago, before signing Sanchez, they also worked out T.J. Yates, EJ Manuel, Josh Johnson and Kellen Clemens. Johnson, who spent time with Gruden in Cincinnati and Tampa Bay, is expected to arrive at the Redskins facility and sign with the team as early as Wednesday, a source tells ESPN's Josina Anderson.

"I don't know what to say," Redskins running back Chris Thompson said. "It's unfortunate. I don't know what it is. It's just ... man, I honestly don't know what to say. To lose two quarterbacks in one year, I've never seen anything like it. It's just tough."

McCoy got hurt on the final play of the first quarter when he was tackled and his leg whipped around, hitting safety Malcolm Jenkins. But McCoy stayed in to finish the final two plays of the series, completing two passes for 15 yards. He appeared to be in anguish on the sideline, trying to walk off the injury. He then was escorted to the locker room. He did not need to go to a hospital, so he was in the locker room for the rest of the game.

It's a crushing end to the season for McCoy, who attempted just 11 passes between the start of 2015 through Week 10 this season, playing behind Kirk Cousins and then Smith. The Redskins believed McCoy could still lead an effective offense because of his experience: He was in his fifth year of Gruden's system. His teammates liked him for his leadership.

But injuries have highlighted McCoy's career. He started four games in 2014 for Washington, but an injured neck sidelined him for the final two games. He also missed the final three games of 2011 with Cleveland after suffering a concussion.

Before leaving Monday, McCoy had completed all four of his throws for 50 yards, leading a field goal drive. After the game, teammates looked deflated in the locker room, a second straight season derailed by injuries.

"I don't know, man, it sucks," left tackle Trent Williams said. "I mean it's hard to describe. You worry about the person more than the football player, but we all out here putting it on the line. When you see one of your fellow comrades go down, it really hurts."

McCoy's injury left Sanchez as Washington's only quarterback. The Redskins signed Sanchez after starter Alex Smith broke his leg in Week 11 and was lost for the season. Sanchez had not played in a game since the Dallas Cowboys' 2016 season finale, in which he completed 9 of 17 passes for 85 yards and two interceptions in a 27-13 loss to the Eagles. Monday, Sanchez completed 13 of 21 passes for 100 yards. He led a two-minute drive that resulted in a field goal before halftime. But he threw for just 38 yards in the second half.

"There's no excuses," Sanchez said. "To be totally honest, nobody cares. Nobody cares. You're charged with a job. You get paid to play this game. You get paid to go win. That's what people expect."

The Redskins signed Sanchez in part because Kevin O'Connell, their passing game coordinator/quarterbacks coach, and offensive coordinator Matt Cavanaugh both were with Sanchez with the New York Jets. O'Connell, a former Jets quarterback, played with him and actually called the plays when Sanchez was in the game Monday, having put together a few packages for him. Sanchez had not practiced with Washington until this past week. In fact, Gruden said afterward, they had more plays for their third-string quarterback (Kevin Hogan) in the first preseason game than they had for Sanchez on Monday. They had a wristband for Sanchez.

"We tried to get him comfortable," Gruden said.

That was difficult at times. He's throwing to receivers he barely knows and hasn't worked with. McCoy had familiarity with this group, which is why Washington felt OK about a final push. Sanchez does not have that with this group. He did receive a number of "we're behind you" talks from teammates after the game.

The Redskins also liked that he was 4-2 in playoff games, giving him experience in tense situations. The final four games now qualify as tense, as Washington remains alive for the playoffs but perhaps in name only, since Redskins have lost four of their past five games. They host the New York Giants on Sunday.

"I've seen just about everything in this league, except for a Super Bowl," Sanchez said. "With this group and these coaches, we'll be able to handle anything. You can't think on Tuesday. We've got to beat the Giants."