Jared Allen went into last year's season finale against the Bears needing 4 1/2 sacks to break Michael Strahan's NFL single-season mark of 22 1/2.
Strahan survived as the Vikings defensive end had 3 1/2 sacks to finish with a team-record 22.
This year, Strahan's grip on the record doesn't look nearly as strong heading into the season's final two weeks. J.J. Watt, a 5-technique end (a player who lines up on the outside shoulder of a tackle) in Houston's 3-4 front, and Aldon Smith, an outside linebacker in the 49ers' 3-4 front, are tied with 19 1/2 sacks.
Allen said he thinks the record will fall. At some point.
"I said it at the beginning of this year that I think 25 is a realistic number in the way this league is, especially with the 3-4 linebackers," Allen said. "You got Aldon Smith, who basically is a defensive end. You got [Dallas'] DeMarcus Ware, who basically is a defensive end with the athletic ability of a linebacker standing up and coming off the edge. Those are serious matchup problems. I think it's definitely attainable."
Watt already has more sacks than any 3-4 defensive end has had since sacks became an official stat in 1982.
"What J.J. Watt is doing is crazy from that 5-technique position," Allen said. "That's like a once-in-a-lifetime, praise-God-that-thing-is-happening because you don't see that very often."
Left defensive end Brian Robison has played 92 of a possible 93 games since the Vikings drafted him in the fourth round in 2007. It's looking more and more like he will miss another one on Sunday in Houston.
Robison, who suffered a Grade 3 sprain of his right shoulder in last Sunday's victory at St. Louis, didn't practice again on Thursday.
"He's making some progress," coach Leslie Frazier said. "We'll see what he can do tomorrow."
Frazier said Robison wouldn't play if he can't show some level of right shoulder use at Friday's practice.
"We'd have to see him do a little pushing," Frazier said. "We'd have to see him do something because of the nature of the injury and the position that he plays. It's possible, but we'll see tomorrow."
Frazier said the Vikings have had other players who have managed to play with a Grade 3 sprain, but added that "everybody is different."
• Cornerback Chris Cook appears set to come off injured reserve. He has missed the past six games because of a broken right arm. "He's made a lot of progress from last week to this week," Frazier said. "We'll see how he does tomorrow. It looks like he's heading in the right direction. It's just a matter of how much we can play him. We'll determine that probably [Friday] when we sit down and talk about it as a staff."
• Left tackle Matt Kalil missed his second consecutive practice because of an illness.
• Cornerback Antoine Winfield was limited again in practice. The Vikings have been resting the 35-year-old late in the season.
• Kalil, Adrian Peterson and Allen topped their respective positions among NFC players as the fan voting portion for the Pro Bowl came to an end. Pro Bowl teams will be named Wednesday.