– The no-longer-first-place Vikings trudged into the visiting locker room at FedEx Field late Sunday afternoon, unsnapped their helmets, yanked off their shoulder pads and plopped down on undersized stools to ponder when this slide might end.

After losing another game and another offensive tackle, they were at a loss for words.

The NFL’s last unbeaten team has not won a game since Oct. 9. In their latest loss, 26-20 to the Washington Redskins, the Vikings dug themselves out of an early 14-0 deficit and scored three second-quarter touchdowns to seize a six-point lead at halftime.

But the offense did not score again, and the once- dominant defense let the Redskins advance into field-goal range on four consecutive possessions during the second half. Despite that, they had two chances in the fourth quarter to reclaim the lead. In the end, though, what was left of their offensive line cost them again in the final minutes.

After five straight wins to open the season, the Vikings have now lost four in a row.

“I am concerned obviously, but I still believe,” coach Mike Zimmer said of the trajectory of his team. “I believe if we do a couple things here and a couple things there, we are going to win games. I just feel like if we can get over the hump and can just keep fighting until we do that, positive things will happen. But … it doesn’t look like that right now.”

Each of these back-to-back-to-back-to-back losses has unraveled a little differently, but the obvious common thread among them was the performance of the offensive line. In this one, the Vikings averaged 2.6 yards per carry, twice got stuffed on third-and-1 in the third quarter and surrendered two late sacks during a failed comeback bid.

The final takedown of quarterback Sam Bradford came on fourth-and-long, as starting left tackle Jake Long was still being carted to the locker room with an injury to his left Achilles’ that will likely end his season. Jeremiah Sirles subbed in for him and immediately allowed Redskins outside linebacker Preston Smith to blow by him. Game over.

“I’ve got to make that block,” Sirles said. “I’ve got to give Sam time to throw.”

Smith also intercepted Bradford on the previous possession, surprising him by dropping into coverage, deflecting a quick pass and grabbing it out of the air with his left hand.

“It’s frustrating,” Bradford, who threw for 307 yards, said after another inconsistent offensive performance. “For us to get back on track, we just have to go out there and execute. …. We were able to do it early in the year. We’ve shown flashes of it.”

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The suddenly vulnerable Vikings defense, meanwhile, allowed the Redskins to score on six of nine possessions before their final kneeldown. Kirk Cousins threw for 262 yards and two touchdowns, one on each of the home team’s first two drives. Rookie running back Robert Kelley rumbled for 97 yards on 22 carries.

“We’ve got to capitalize on opportunities. We’ve got to create more turnovers. We’ve got to be better on third down,” defensive end Brian Robison said after a second straight opponent scored 20-plus points. “There’s a lot of things that aren’t happening for us right now and we’ve got to figure out what we got to get back to doing.”

Down 14-0, the Vikings finally pieced together their first scoring drive midway through the second quarter, after Bradford lobbed a pass to wide receiver Stefon Diggs, the Maryland native playing his first professional game in his home state, for a 36-yard gain. On his third carry from the 1, Matt Asiata finally got over the goal line.

Diggs finished with 164 yards after totaling 13 catches for a second week in a row.

The Vikings then stunningly stole the lead before halftime. They tied it up after a 20-yard touchdown reception by tight end Kyle Rudolph. Then after a Redskins fumble, Bradford tossed a 3-yard touchdown to wide receiver Adam Thielen to put them up 20-14.

But struggling kicker Blair Walsh missed the extra-point try, and the Vikings, in their second game under interim play-caller Pat Shurmur, did not score again.

The Redskins tied the score at 20-20 with a pair of field goals during the third quarter. A 50-yarder by Washington’s Dustin Hopkins gave them back the lead in the fourth. He hit another with less than three minutes remaining.

The defeat knocked the Vikings into a first-place tie with the Detroit Lions in the NFC North, but the Lions hold the tiebreaker after stunning the Vikings 22-16 in overtime a week ago at U.S. Bank Stadium.

For the second week in a row, Zimmer stood in the locker room Sunday, pointed out positives to despondent players and told them he liked how they fought in a losing effort.

“After a while you kind of get tired of hearing that,” left guard Alex Boone said. “You can only say you played so tough for so long until it doesn’t count anymore. These are games we’ve got to win.”


Matt Vensel covers the Vikings for the Star Tribune. matt.vensel@startribune.com