Throw in Ben Tate, Derrick Ward and Chris Ogbonnaya, and a team that once struggled to find a dependable running back is now overstocked.
Foster was on Houston's practice squad for much of 2009 before last year's breakout season, when he rushed for 1,616 yards and 16 touchdowns. He knows he can't rely on what he did last year to be successful in 2011.
"The crazy thing about this league is that -- coach (Gary Kubiak) says it all the time -- that you have to prove yourself every single day," Foster said. "You could lead the league in rushing one day and the next day they'll forget you fast. You have to keep on making your mark."
Foster sat out much of Friday's practice after experiencing tightness in his hamstring, but should be OK. It was a setback that Kubiak said highlighted the need to have a deep group at the position, as players get banged up throughout the season.
"We're going to end up with four dang good ones and we may be in a situation where we can keep five," Kubiak said. "So we're strong at that position right now, but y'all know how this works. You come out one day or play one preseason game and you go from having a bunch of them to something happening. So let's just keep our fingers crossed that they're all going to be there at the end and we're going to have a good group."
Slaton had 1,282 yards rushing with nine touchdowns as a rookie in 2008, but hasn't done a lot since then while dealing with injuries and the emergence of Foster. He's healthy now, and the Texans believe he could add to the running game.
Tate was selected in the second round of the 2010 draft after rushing for 1,362 yards and 10 touchdowns as a senior at Auburn. He was expected to see limited playing time last season, but missed his entire rookie year after breaking his ankle in Houston's first preseason game.
"I'm very anxious to get back to a preseason game and get to show everyone, the fans, the organization, teammates, what I can do," he said.
Houston has so many options at the position that the team may not be able to keep all of them.
"He's in a battle," Kubiak said of Tate. "He's working as a fourth guy right now and that's a humbling experience. You come out here after you miss all last year (and) it's a very competitive situation, and we've got a nice problem back there. So we'll see how it works out."
Ogbonnaya spent last season on Houston's practice squad. After a successful career at Texas, he spent one season mostly on the St. Louis Rams practice squad.
The 30-year-old Ward spent the first five seasons of his NFL career with the Giants, where he ran for a career-high 1,025 yards in 2008. He appeared in each game for Houston last season and finished with 315 yards rushing and four touchdowns.
Quarterback Matt Schaub said a dynamic running game took pressure off the passing game.
"It allowed us to control the tempo a little bit more, keep our situations and our downs manageable ... and we were able to execute better in the red zone because the field is shorter," he said. "The defense doesn't have as far to defend in the pass game, so running the ball down there was of the utmost importance. It just helped us keep everything manageable. So it helped me out tremendously."