Steven Jackson has missed practice this week with a groin injury.

Those surprised, raise your hand. If you selected Jackson among the top four picks, scared off by Maurice Jones-Drew's preseason injury or Ray Rice's ability to sustain his production, you might be pounding your head on your desk or repeatedly yelling "Frank Gore!" instead of raising said your arm.

"The leg's still tight, the groin's still tight, so it's just one of those injuries where just time is what's really going to heal the injury," Jackson told reporters Thursday.

Just a guess: He's not playing this week.

Jackson missed four games in both 2007 and '08, and in the 42 games he's played since 2007, he has a mediocre total of 19 touchdowns.

Sunday's opponent, the Seahawks, rank fifth against the run and are allowing only 2.6 yards per carry.

If Jackson is active, you have to play him. If he's out, backup Kenneth Darby -- who had 14 carries for 49 yards and one TD last week -- should get most of the work, since No. 3 back Keith Toston is also nicked up.

If Jackson is inactive, Darby is a decent flex play in PPR formats. He had a combined 37 receptions in 2008 and '09.

Jackson might be resting up for Oct. 10. In Week 5, the Rams will play at Detroit, the league's worst run defense.

Let's look at four more running backs who have had injury issues (note: We'll address Ray Rice's knee bruise in a column for Friday's print and online editions):

-- Chargers rookie Ryan Mathews returned to practice after sitting last week because of an ankle injury. If he plays Sunday against Arizona, as he should, he should be in your lineup. The Cardinals rank 31st against the run and are allowing 146.3 yards rushing per game.

-- Clinton Portis, who shared carries with Ryan Torain last week because the former has a wrist ailment, seems to be a go for Week 4. Sunday's opponent, the Eagles, have struggled against the run (No. 23, 128.7 yards per game, three touchdowns). Portis is a low-level No. 2 back at best, though, after rushing for all of 634 yards in 11 games since the start of last season.

-- The Broncos haven't ruled Knowshon Moreno out, but he isn't practicing because of a hamstring injury and seems certain to miss Sunday's game at Tennessee. If Moreno is out, Laurence Maroney is a better play than Correll Buckhalter, but neither is a top-25 back this week.

-- Just when it seemed Pierre Thomas had the Saints' rushing workload to himself, he injured his ankle last week and will be a game-time decision Sunday against Carolina. If Thomas sits, rookie Chris Ivory, who had seven carries for 13 yards last week, is a flex play vs. the Panthers (No. 14 vs. the run).

Stat of the week

8.5: Chiefs running back Jamaal Charles' average yards per touch this season. He has 34 carries for 238 yards and one touchdown, and five catches for 92 yards. Meanwhile, starter Thomas Jones, who has 18 more carries than Charles, is averaging 4.1 yards on 54 touches.

The Chiefs are 3-0, so obviously it's working. But the fantasy geek in many of us wonders if Todd Haley and Charlie Weis have forgotten that Charles held up just fine with an increased amount of touches in the second half of 2009.

Programming note: Check back late Thursday night or Friday morning for a column in the N-H's online Sports section that will break down five of the most disappointing players from a fantasy perspective in the first three weeks.