The script was remarkably fitting on a night that started one way and veered completely in an opposite direction.

Down to only 42 players in uniform because of a rash of injuries, the Vikings secured their first victory on American soil Thursday night in unlikely fashion: With Christian Ponder leading a comeback and their defense holding firm.

Strange developments, right?

Matt Cassel provided a steady hand in relief of an injured Ponder and the defense cranked up the pass rush after a miserable first half as the Vikings halted their four-game losing streak with a 34-27 victory against the Washington Redskins at Mall of America Field.

The Redskins had three consecutive incompletions from the Vikings 4-yard line in the final 38 seconds to end a potential rally, allowing the 2-7 Vikings and their fans to breathe.

"There were many times during the course of that game when they could have said, 'Oh, no, here we go again,' " coach Leslie Frazier said. "But they didn't. They just kept battling and believing that we were going to get a win."

In one frenetic stretch, Ponder finally looked like the quarterback the Vikings desperately have wanted since drafting him 12th overall in 2011. He made critical plays with his arm and feet. He didn't look skittish when the pocket collapsed. And he didn't appear nervous with a double-digit deficit on the scoreboard.

But in a cruel bit of irony, Ponder didn't get a chance to finish what he started thanks to a shoulder injury that sent him to the locker room at the end of the third quarter.

With his team trailing 27-14 in the third quarter, Ponder directed back-to-back touchdown drives. The first one ended on a 28-yard touchdown pass to tight end John Carlson.

On the next possession, the Vikings faced a third-and-12 from the Washington 43. The Redskins' pass rush chased Ponder from the pocket, but he found Jarius Wright standing along the sideline for a 28-yard completion.

Then, on the next play, Ponder scrambled to his left and sprinted for the end zone. He dived for the goal line but was drilled hard by DeAngelo Hall, knocking the ball loose out of bounds at the 1-yard line.

Ponder got up holding his left arm and returned to the locker room. Frazier said Ponder dislocated his left shoulder but did not give a timetable for his return. Ponder had his arm in a sling after the game. Frazier expressed hope that Ponder would be available for the Vikings' next game, at Seattle.

Ponder completed 17 of 21 passes for 174 yards and two touchdowns with one interception.

"I think Christian is really growing," Frazier said. "He's becoming more confident, more in command. He's growing as a leader. Just the fact that he never got shaken, even after that interception [on the first drive]. That did not cause him to go into the tank and have self-doubt. He came back and played some of his best football."

Cassel replaced Ponder, and on his first play he handed the ball to Adrian Peterson, who went 1 yard for a touchdown to give the Vikings a 28-27 lead.

The Vikings defense took over at that point. Shredded in the first half, the Vikings turned up the heat on Robert Griffin III. The Vikings collected three sacks in the fourth quarter alone. Veteran Pro Bowl tackle Kevin Williams collected 2½ sacks and four quarterback hits.

"We always play hard, [it's] just not executing," Williams said. "That's been the story all year. Shoot, we had to do it eventually. We put a second half together."

Their first half was a mess. Members of the Vikings defense fumed over coaches' play calls after a late-game meltdown at Dallas on Sunday. Defensive coordinator Alan Williams returned the favor in the halftime locker room.

The Redskins scored on all four of their possessions in the first half and led 24-14. They rolled up 288 total yards and 18 first downs. They converted seven of eight third-down attempts, which enabled them to control the ball for 20 minutes, 40 seconds.

The Redskins' ease in moving the ball was reminiscent of Green Bay's offensive dominance two weeks ago. The Packers scored on all eight possessions before ending the game with kneel-downs, did not punt once and converted 13 of 18 third-down opportunities.

Griffin completed 16 of 21 for 179 yards and three touchdowns with a 140.7 passer rating before halftime. Alfred Morris rushed 17 times for 88 yards.

Williams let his players have it at halftime.

"He was more fired up than I've ever seen," Frazier said. "But it was good. We needed it. We needed a kick in the pants."

The Vikings responded with an inspired effort in the second half. They even forced a punt, which is something they didn't do against the Green Bay Packers at home two weeks ago or in the first half Thursday night.

That led to a giddy response by Frazier when asked about seeing a punt.

"I was going, 'Hurrah, hurrah,' " he said, arms raised above his head. "We got another one and another one. We're going to do this the second half of the season. We'll make people punt."