RENTON, Wash. — Matt Hasselbeck’s painkilling injections not only saved the Seahawks’ weekend, they may have saved their season.

Seattle (2-3) is suddenly one game out of first place in the mild, mild NFC West, one week after Hasselbeck couldn’t breathe without pain and the Seahawks were gasping on the verge of irrelevance.

Then came Hasselbeck willing himself through a week of practice before Sunday’s 41-0 rout of Jacksonville, in which he threw four touchdown passes while playing for the first time in three weeks. Now, the Seahawks can get back to .500 with a win at home Sunday against the so-far mediocre Arizona Cardinals (2-2).

Hasselbeck called Monday a “real test, pain-wise.” He apparently passed it. Coach Jim Mora said Hasselbeck will practice this week on an “as-tolerated” basis. He is expected to start again on Sunday.

“I wouldn’t wish this on anybody,” Hasselbeck said of his pain.

How big is his return? Mora noted that entering last weekend, NFL teams were 2-11 this season when playing without their starting quarterback.

After Arizona, Seattle gets its off week. It will be a godsend for a team that played without seven more injured starters against the Jaguars.

“It’s only one game, but, yeah, the clouds lifted a little bit for us,” Mora said. “And not only that, we see good things on the horizon with some of the guys we are going to get back.”

That includes three-fifths of the starting offensive line. Walter Jones, the nine-time Pro Bowl left tackle, will give his twice-operated-on left knee another push after the bye on Oct. 25. Left guard Rob Sims and right tackle Sean Locklear are expected back from sprained ankles for the Nov. 1 game at Dallas.

Nothing made Mora happier than seeing his three-time Pro Bowl quarterback at lunch Monday. He said Hasselbeck “seemed fine. He didn’t take any enormous hits (Sunday).”

Hasselbeck had missed the previous 2½ games because of a hit high in the back from San Francisco’s Patrick Willis during a dive for the goal line on Sept. 20. Last Monday, the 34-year-old was in what Mora called “excruciating pain” while trying to accelerate his rehabilitation, feeling the urgency to rescue his team.

The captain came through.

He threw for his most touchdowns in two years, and completed 18 of 30 for 241 yards against Jacksonville’s 30th-ranked pass defense. He ran for another 23 yards, including for 12 on a scramble he ended by sliding safely in the open field. He even attempted to throw a block downfield against cornerback Derek Cox on a 22-yard reverse-field run by Justin Forsett in the third quarter.

So what that he whiffed, though Hasselbeck joked, “I thought I did (block him).”

Mora called Hasselbeck’s return “courageous, but not surprising.”

“Sometimes (with) guys who are cerebral like Matt, you discount their toughness,” the coach said. “Matt’s a tough guy, mentally tough and physically tough. These players in the locker room have a lot of respect for him. We certainly do as coaches.

“I kind of expected him to go out and play like that, just knowing the competitor he is. I really respect him.”

Hasselbeck’s biggest and most important accomplishment was avoiding big hits. He dived away from one and to the ground on a 44-yard touchdown pass to Nate Burleson in the second quarter.

“He did a nice job of avoiding hits,” Mora said, “even when we missed blocks.”

There’s likely be more missed blocks.

Two more fill-in starters got hurt on the offensive line: Brandon Frye at left tackle and Mansfield Wrotto at left guard. Mora said Wrotto should be able to play this weekend, but Frye was still having tests for a neck injury sustained early in Sunday’s game.

That forced Kyle Williams, who was promoted from the practice squad on Saturday, to become Seattle’s Plan D left tackle. And Williams played through a sprained knee sustained on a first-half field goal.

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