The Vikings middle linebacker said he has had similar swelling and pain in his knee before and has been able to play in the game.
Based on a similar experience from last November, Vikings Pro Bowl middle linebacker E.J. Henderson said he's "pretty confident" he will play in Sunday's home opener despite missing practice Thursday and Friday because of a sore and swollen left knee.
"I think we had one episode last year where it swelled up a lot," Henderson said. "We pretty much had to do the same thing -- drain it, treat it and I made it out there Sunday. This is nothing out the ordinary. Just maybe a little more swelling, a little more pain, but it's something that we're dealing with, and hopefully I'll be ready to rock on Sunday."
Henderson had fluid drained from the knee Thursday and said he was feeling better Friday. An X-ray on Thursday revealed no structural damage.
Coach Leslie Frazier is cautiously "hopeful" that Henderson will play but called it a game-time decision based on a pregame workout at the Metrodome before the team plays the Tampa Bay Buccaneers. Officially, Henderson is listed as questionable, meaning he has a 50 percent chance of playing.
"The swelling is down, so that was a good thing," Frazier said. "But he still looked tender. ... When he said that he was struggling a little bit, you have to pay attention because he never talks about injuries at all. It's not who he is. If there's anybody who can play through things, E.J. Henderson can."
Overnight, the Vikings went from being injury-free coming out of Week 1 to potentially losing a starter at the position with the least depth.
Jasper Brinkley, a reliable backup the past two years, had hip surgery and was placed on injured reserve two weeks ago. That forced the Vikings to scramble after making their final cuts Sept. 3.
They claimed Xavier Adibi, a career 3-4 inside linebacker, off waivers from Houston on Sept. 4. But Adibi, a four-year veteran with eight starts, isn't ready to assume the starting job in a 4-3 defense. So the Vikings, at this point, would move starting weak-side linebacker Erin Henderson to the middle and insert Kenny Onatolu, a special teams player, at weak-side linebacker. Signing another linebacker was discussed but dismissed, Frazier said.
The move would be a significant change for Erin Henderson. He has just one NFL start, which came on the weak side last Sunday.
"Your vision has to be a lot different and your responsibility is a lot different [at middle linebacker]," Frazier said. "You're calling the defense, you're getting people lined up. You're making sure that the front is where it should be, so there's a lot more responsibility in that role as a middle linebacker."
Frazier said there's still a possibility that strong-side linebacker Chad Greenway will call the defense and line people up.
Onatolu, meanwhile, has no NFL starts. He also spent most of the preseason recovering from a broken foot and appeared lost in pass coverages in the preseason finale against Houston.
Onatolu would come off the field in the nickel, which the Vikings employ about 50 percent of the time. But that also means Erin Henderson would be asked to play about twice as many snaps.
E.J. Henderson said he often has swelling in the knee area where a metal rod was inserted during surgery to repair a broken left femur in 2009. Henderson normally would have had a magnetic resonance imaging (MRI) test, but the metal rod blurs the image, Frazier said.
Henderson said he believes the reduced number of preseason snaps combined with an inordinately high amount (77) in the regular-season opener might have contributed to the extra swelling and soreness.
"I've felt that swelling before," said Henderson, who practiced Wednesday. "I expected it to flare up a little bit. But just not that much."
Although Erin Henderson said he's ready to start in the middle, he doesn't think it will be necessary. Asked what he thinks are the chances of his big brother playing Sunday, Erin didn't hesitate.
"About 99 percent," he said. "I know my guy. I know my brother. We come from a place where, if you can, you do."
|Seattle - LP: F. Hernandez||0||FINAL|
|Cleveland - WP: J. Masterson||6|
|Arizona - LP: W. Miley||1||FINAL|
|Miami - WP: R. Nolasco||2|
|Cincinnati - LP: A. Chapman||2||FINAL|
|Philadelphia - WP: A. Bastardo||3|
|Houston - LP: L. Harrell||0||FINAL|
|Pittsburgh - WP: J. Locke||1|
|Los Angeles - LP: K. Jansen||2||FINAL|
|Atlanta - WP: L. Avilan||5|
|Tampa Bay - WP: M. Moore||3||FINAL|
|Baltimore - LP: C. Tillman||1|
|Boston - WP: J. Lackey||5||FINAL|
|Minnesota - LP: P. Hernandez||1|
|Milwaukee - LP: K. Lohse||2||FINAL|
|St. Louis - WP: J. Gast||4|
|NY Mets - WP: S. Rice||4||FINAL|
|Chicago Cubs - LP: K. Fujikawa||3|
|Chicago WSox - LP: J. Peavy||2||FINAL|
|LA Angels - WP: J. Vargas||6|
|Kansas City - LP: K. Herrera||3||FINAL|
|Oakland - WP: J. Blevins||4|
|Washington - LP: D. Haren||4||FINAL|
|San Diego - WP: A. Cashner||13|
|San Francisco - LP: B. Zito||0||FINAL|
|Colorado - WP: J. Nicasio||5|
|Detroit - LP: J. Ortega||8||FINAL|
|Texas - WP: R. Ross||11|
|Red Bull New York||1|
|Sporting Kansas City||1||FINAL|
|Real Salt Lake||4||FINAL|
|Aug 9 - vs. Houston||7 pm|
|Aug 16 - at Buffalo||6 pm|
|Aug 25 - at San Francisco||7 pm|
|Aug 29 - vs. Tennessee||7 pm|
|2013 regular season|
|Sep 8 - at Detroit||Noon|
|Sep 15 - at Chicago||Noon|
|Sep 22 - vs. Cleveland||Noon|
|Sep 29 - vs. Pittsburgh (in London)||Noon|
|Oct 6 - Bye|
|Oct 13 - vs. Carolina||Noon|
|Oct 21 - at. NY Giants||7:40 pm|
|Oct 27 - vs. Green Bay||7:30 pm|
|Nov 3 - at Dallas||Noon|
|Nov 7 - vs. Washington||7:25 pm|
|Nov 17 - at Seattle||3:25 pm|
|Nov. 24 - at Green Bay||Noon|
|Dec 1 - vs. Chicago||Noon|
|Dec 8 - at Baltimore||Noon|
|Dec 15 - vs. Philadelphia||Noon|
|Dec 22 - at Cincinnati||Noon|
|Dec 29 - vs. Detroit||Noon|