The Post's Jason Reid reports an optimistic outlook for the Redskins after their first win and just before heading into their bye week. Photos by AP, Getty and the Washington Post. (The Washington Post)

With his team already trailing 14-3 only four minutes into the second quarter, rookie cornerback David Amerson badly wanted to make a play.

The second-round pick already had been beaten on a 34-yard pass play on which Oakland Raiders wide receiver Denarius Moore went up the right sideline and made a catch that set his team up for its second touchdown of the game.

That marked the third time in as many weeks Amerson had allowed an assigned receiver to get the best of him for a pass play of 30 yards or more. So Amerson — remembering something veteran cornerback DeAngelo Hall had told him — looked for a way to redeem himself.

He found the opportunity on third and five from the Oakland 43-yard line. Matched up with Moore again, Amerson recognized that the wide receiver was running a half-speed crossing route. Picking up his speed, Amerson cut underneath the route, timed Matt Flynn’s pass perfectly and plucked it out of the air.

Amerson raced 45 yards untouched toward the end zone, stretched the ball out as he neared the goal line and scored before getting mobbed by teammates.

“That was especially big for Amerson to get that after giving up that one big play a little earlier,” Hall said. “That’s what I told him: ‘In this league, you give up one, you make one.’ He wound up getting one and just took it to the house. It was his first career pick, first career touchdown. That’s all you can ask for.”

That play cut the Raiders’ lead to 14-10, and it also wound up changing the game for Washington. Defensive players said it energized their unit and spurred them to hold the Raiders in check the remainder of the half.

It was the second pick-six of the season for Washington’s defense and the third defensive touchdown overall. Hall scored on an interception return last week, and he returned a fumble for a touchdown in Week 1.

The interception was one of two takeaways for the Redskins, who in the third quarter recovered a Flynn fumble.

The much-maligned defense, which had set the NFL record for yards allowed in the first three games of the season, turned in its most impressive showing of the season. The Redskins recorded seven sacks, gave up only seven points, limited the Raiders to 298 total yards and denied them on 12 of 17 third-down conversion attempts.

“I talked to them right after the game. They did a heck of a job, any time you get seven sacks in the National Football League and return an interception for a touchdown,” Coach Mike Shanahan said. “David Amerson did a great job. We couldn’t get a lot going offensively. They kept us in the game, and we managed to make a couple of plays later in the game.”

The seven offensive points marked the fewest allowed by Washington since Week 11 of 2012, when it limited the Philadelphia Eagles to six.

The Redskins hadn’t had seven sacks in a game since the 2011 season. Ryan Kerrigan recorded two and now leads the team with five. Brian Orakpo recorded two as well and now has three. Nose tackle Barry Cofield also had two — the first multiple-sack day of his career — and backup linebacker Darryl Tapp added another.

“We needed that so bad. It really feels good,” Kerrigan said of his unit’s outing. “Seven was kind of the magic number today. To give up only seven points, have seven sacks, we scored seven points on defense. Man, it’s a great feeling in here right now.”