LANDOVER, Md. -- It was as ugly as the gloomy, rainy weather -- and the mud-heavy playing surface -- at FedEx Field on Sunday, but the San Francisco 49ers once again found a way to take care of business, this time against the Washington Redskins in a game many expected to be much easier.

However, Mother Nature made sure nothing was easy in a game that could best be described as an underwater rock fight. The Niners did just enough to beat the Redskins 9-0 and improve to 6-0 for the first time since 1990. For the dominant San Francisco defense, it was the first shutout of the season and the franchise's first since Week 1 of the 2016 season. It was the first NFL game to finish 9-0 since Week 8 of 2010, when the Green Bay Packers beat the New York Jets.

No, this wasn't pretty and it wasn't nearly as convincing as most of their other victories, but it counts just the same.

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Offense was hard to come by for both sides, but San Francisco managed just enough offensively to get the job done. The score was tied 0-0 at the half and the Niners were the first team since the 2011 Packers to be 5-0 and enter a half scoreless. Robbie Gould provided all the points with three second-half field goals.

In a season that's long and a league where winning isn't easy, more difficult challenges figure to be in the offing. That's especially true next week, when the Niners host the Carolina Panthers.

So far this season, the Niners have proved to be up for every task. Even one drenched in rain.

Describe the game in two words: Total slog. It began raining early in the morning in the Washington D.C. area, which made one of the worst fields in the NFL an even sloppier track. It also made it nearly impossible for either offense to get in a rhythm.

Pivotal play: With 1:20 left in the third quarter, the Redskins appeared to finally be in business offensively, driving to the Niners' 29. On first down, the Redskins handed it to running back Adrian Peterson, who cut to the right and was met by San Francisco linebacker Kwon Alexander, who pried the ball away.

Defensive lineman Jullian Taylor recovered it and returned it to San Francisco's 41. Washington never threatened again.

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Promising trend: While the injuries continue to mount, the Niners continue to find players to step in and produce in place of those who are ailing. For an offense that was already missing tackles Joe Staley (fibula) and Mike McGlinchey (knee), fullback Kyle Juszczyk (knee) and receiver Deebo Samuel (groin) and a defense without tackle D.J. Jones (hamstring) and cornerback Ahkello Witherspoon (foot), the Niners needed all hands on deck Sunday. That became even more true, as receiver Marquise Goodwin and running back Matt Breida departed for stretches of the game to be evaluated for head injuries.

On Sunday, it was the likes of receivers Kendrick Bourne and Richie James Jr. -- subbing for Samuel and Goodwin -- providing a much-needed spark with big catches for gains of 28 and 40 yards, respectively. Taylor filled in for Jones to help settle the run defense, coming up with a key stop on fourth down and recovering a fumble.

And this time, the Niners actually got some good news on the injury front, as Breida and Goodwin were cleared of any concussion issues.