Eventually, the memory may fade. Someday, the signature play could be lost among many. Perhaps rookie running back Roy Helu’s big moment won’t hold up quite so well over time.

That’s certainly what the Washington Redskins hope. Actually, they’re counting on it. Because as much as Helu impressed during Sunday’s 23-17 victory over the Seattle Seahawks — especially in sparking the team’s fourth-quarter rally with a highlight-tape touchdown run — the Redskins need even more from him.

Helu’s personal-best 108 yards rushing (with a 4.7-yard average) in only his second career start? Good stuff, but the Redskins already knew the young man runs hard.

His seven receptions for 54 yards? For some time, Washington has been aware of Helu’s solid receiving skills.

Even Helu’s pass-blocking, the weakest part of his performance, not surprisingly, has steadily improved throughout his first NFL season. The fourth-round draft pick from Nebraska has shown just about everything the coaching staff expected.

Against the Seahawks at CenturyLink Field, Helu delivered the unexpected. He had a game-changing performance. Helu’s breakout outing provided key information Washington needs to determine whether it currently has a viable long-term option at running back on the roster.

In helping the Redskins finally end their depressingly long losing streak at six games, Helu did much more than simply play well. He continued to provide answers to one of the many questions on the Redskins’ long list.

For weeks, the Redskins’ season has been all about fact-finding. They’re gathering favorable data on Helu.

Things have been trending positive for some time, and Helu’s increased workload in practice last week signaled Coach Mike Shanahan’s intention to accelerate the evaluation process against Seattle.

No matter how much talent running backs possess, they usually must prove they’re competent in pass protection to earn significant playing time.

Helu has shown marked improvement in executing the Redskins’ protection schemes, prompting Shanahan to determine “he was ready. He was ready to play a full game in protection against a good defensive team.”

He nailed the other stuff, too.

Helu seized his opportunities in the rushing attack and passing game. He was determined. He was consistent. He was a leader for Washington, which trailed by 10 points early in the fourth.

Helu ignited the Redskins’ comeback by “running wild,” left tackle Trent Williams said. “We knew he was capable, so that’s not a surprise. But when he made that play, I think everybody was like, ‘Man, he’s a handful.’ And that was exactly what we needed right there.”

The Seahawks went ahead, 17-7, with 12 minutes 45 seconds remaining in the game on a 15-yard touchdown pass from quarterback Tarvaris Jackson to wide receiver Golden Tate. After a fast start in the opening quarter, Washington’s offense reverted to form and did little for most of the game.

But quarterback Rex Grossman got hot on Washington’s first possession after Seattle took a double-digit lead, connecting on his first four passes on the drive, including one to Helu for seven yards on first down. Following Grossman’s only incomplete pass, the Redskins called a running play for Helu.

It was a good one.

Grossman, flanked by Helu on his left in the shotgun formation, took the snap and pitched the ball to Helu, who ran left. As Helu approached the first-down marker, Seattle cornerback Roy Lewis came up to make the tackle, and it appeared Lewis was in perfect position.

That is, until Helu hurdled the diving Lewis and then ran through strong safety Kam Chancellor’s attempted arm tackle en route to a 28-yard touchdown. The play ignited a celebration along the Redskins’ sideline and began a 16-0 closing kick.

“Once I got the pitch,” Helu said, “the first thing was I [looked to] the edge, and then it seemed like I could get around [the corner]. Right where [Lewis] was, where I hurdled him at, was the first-down marker, and I just wanted to make sure I got it [the first down].

“I didn’t care if the safety came over and killed me in the air. I knew I’d get the first down with forward progress. I came down and ended up breaking the tackle.”

The play of the game, Grossman said. It was one the Redskins desperately needed. No doubt about it.

“It was awesome,” said Grossman, who hugged Helu before stepping to the lectern to address reporters. “He had some hard runs that aren’t always on the highlight reel, but kept us in third and manageable or second and four. We were able to pick up first downs and move the ball.

“Then, obviously, it was one of the most impressive runs I’ve ever seen. To just hurdle somebody and keep moving. . . it was just awesome. That was the play that really got us going there in the fourth quarter to get the win.”

The signs have been there recently, and Helu “got his opportunity and he ran extremely hard,” Shanahan said. “He broke some tackles and made the big plays. . . . I thought he ran extremely hard throughout the whole game.”

Wisely, Helu praised Washington’s offensive line, showing he truly has learned a lot quickly. “I was just a product of them blocking well,” he said.

It was more than just having holes to run through. Helu showed something special. He gave the Redskins a reason to hope — and they’re eager so see what he does next.