On Monday afternoon, the usually nimble Percy Harvin plodded into the Vikings locker room on crutches.

His left ankle was badly swollen and causing him serious pain, the result of a sprain he suffered on a third-quarter run in Sunday's 30-20 loss in Seattle.

Asked if the crutches were a bad sign of how the ankle reacted overnight, Harvin chuckled and shook his head.

"It's not a good sign," the Vikings receiver acknowledged.

As if the Vikings' listless passing attack needed more bad news. After netting only 44 passing yards Sunday, the team's most explosive receiving weapon now might have to miss Sunday's home game against Detroit.

An MRI showed Harvin's ankle was not fractured, but it is sprained in three different places.

Harvin said he planned to take things day by day this week and was still hoping to give it a go against the Lions. Asked if taking this week off would make more sense, especially with a Week 11 bye to follow, Harvin shrugged.

"Does it make sense? To me, no," he said. "But if that's what has to happen, that's what has to happen. I'm shooting to try to play."

Still, the severity of Harvin's injury might ultimately trump his toughness. Initially, when he suffered the sprain on that run late in the third quarter, Harvin feared the worst.

"I thought I was done," he said.

Yet he quickly had his ankle wrapped, tested it on the sidelines and returned to play on the next series.

"When I got to the sideline and the pain went down just a little bit, I thought I could go back in the game," Harvin said. "But as the game ended, it wasn't good."

On Monday, Harvin did not conceal the fact that the swelling in his ankle had significantly increased. But his competitive side wouldn't allow him to rule out playing against Detroit.

"I'm in a lot of pain," he said. "There's a lot of swelling as of right now. My whole ankle all the way around is swollen. So we've got a lot to work to do. It's a long shot. But I'm not ruling myself out."

Nine games into a career year, the demolition-derby style with which Harvin plays might be catching up to him. Suddenly, he has notable injury worries with both legs -- that sprained ankle on the left, plus a sore right hamstring that caused him to miss a half-dozen plays early in Sunday's second half.

Yes, Harvin played through both setbacks. But it was clear he wasn't the same player in the fourth quarter as he struggled to put pressure on his left foot.

His ankle buckled on a routine crossing route with 12 minutes to play, leading to an incompletion. On the next Vikings drive, Harvin didn't have the acceleration or push necessary to prevent a Brandon Browner interception on a deep pass up the left sideline.

The ripple effect

So now what?

Harvin has only missed three games in his career -- in Week 14 of his rookie year and Weeks 13 and 14 in 2010. Those absences were all because of migraine headaches.

With the Vikings passing attack already sputtering, it's hard to imagine what might happen if the NFL's catch-leader couldn't play this week.

Harvin has 62 receptions this season -- that's 34 percent of Christian Ponder's completions. The Vikings' next leading receivers are Kyle Rudolph (27 catches for 242 yards) and Michael Jenkins (26 catches for 295 yards).

It's logical to think rookie Jarius Wright, a fourth-round pick who has yet to be active for any game, could make his NFL debut if Harvin was unable to play.

But replacing the versatility, productivity and overall toughness Harvin has lent to the offense would be darn near impossible. And that would certainly be disconcerting for a one-dimensional offense that has averaged only 105 net passing yards in its past three games and is struggling with protection, blitz pickups, route-running and play-calling.

Now, one of the major strengths of the offense might be off limits, too.