Max Scherzer describes the pain he is feeling from neck spasms and how disappointed he is after his Game 5 scratch. (1:37)

WASHINGTON -- Nationals starter Max Scherzer was scratched from his Game 5 start against the Astros because of spasms in his neck and upper right trapezius.

"Yesterday, he had a little bit of spasms in his right trap and neck," manager Dave Martinez said before the Astros' 7-1 victory Sunday dropped the Nationals into a 3-2 World Series deficit. "They treated it. He woke up today a lot worse."

According to Scherzer, the symptoms were bad enough that he couldn't do anything "menial" when he woke this morning.

"Moment I wake, I couldn't get out of bed," Scherzer said. "I basically just fell out of bed. Picked myself up with my left arm, and I was moving around, just couldn't even move my [right] arm. I just knew at that point I was in a really bad spot."

Righty Joe Ross took Scherzer's place and faced Astros ace Gerrit Cole, but he gave up early two-run homers to slumping rookie Yordan Alvarez and Carlos Correa, lasting five innings as Houston won its third straight at Nationals Park.

"We kind of gave him a heads-up last night," Martinez said after the game. "And when he came in this morning, we told him he was definitely going to start. I thought he did really well, I really did."

Scherzer said he received a cortisone shot in the irritated region of his neck and back. Doctors said it should take about 48 hours for the shot to take effect, which means it's possible that he could pitch in a Game 7 on Wednesday in Houston.

"That's what the doctors believe with this nerve irritation, with a cortisone shot in there, that the neck can take 48 hours, [and] it really will help subside the pain that's being alleviated," Scherzer said. "I'm just hoping that doctors are right and that something can be possible for Game 7."

Game 5 was set up to be a highly anticipated rematch between Scherzer and Cole, who both started Game 1, a 5-4 Nationals win. However, Martinez said Scherzer will continue to undergo treatment, and the club will keep him on the roster rather than petition for an injury replacement.

"We're going to keep him on the roster," Martinez said. "If this gets better in the next 24 to 48 hours, being that we have a day off tomorrow, hopefully he'll be available to pitch one of those two games."

Scherzer, 35, went 11-7 with a 2.92 ERA during the season but was limited to 27 starts because of back problems. He said the new injury appears to be unrelated to that issue, which was more a problem with the lower region of the back.

Scherzer, a three-time Cy Young winner, said his condition shouldn't result in any long-term problems and that avoiding that outcome was one reason he wouldn't have pitched Sunday. But it turned out that fighting through the injury wasn't an option.

"That was one of the dangers of pitching tonight, was that something serious could go wrong," Scherzer said. "But actually I can't even pick up my arm right now."

A 26-year-old right-hander, Ross was 4-4 with a 5.48 ERA in 27 appearances during the regular season, including 4-2 with a 3.02 ERA in nine starts. He was told Saturday that there was a chance he would pitch and was awake in bed Sunday -- he didn't get up until 2 p.m. -- when he got a call from pitching coach Paul Menhart telling him to be ready to start. He received a text from Scherzer five minutes later with the same message.

Fans cheered as he walked to the bullpen before the game. "Definitely noticed the kind of roar, I guess, as I went out on the field, which is pretty cool,'' Ross said. "I would say probably louder than any previous start that I've had.''

Ross allowed four runs, five hits and two walks. He didn't fault himself for Alvarez's go-ahead home run in the second.

"Sinker down and away. I thought it was a good pitch -- a pitcher's pitch,'' Ross said.

He blamed himself for Correa's drive, which made it 4-0 in the fourth.

"Hanging slider, two strikes,'' Ross lamented.

During the early rounds of the playoffs, Martinez helped navigate the Nationals to the World Series by deploying his key arms -- Scherzer, Stephen Strasburg and Patrick Corbin -- as both starters and relievers. When asked if that might have contributed to his problems, Scherzer dismissed the possibility.

"Absolutely not," Scherzer said. "This [is] just another thing that was a little thing that turned into a big thing that turned into a giant thing."

The Associated Press contributed to this report.