The Texans will be without Arian Foster.

For how long is unknown. 

"He's going to miss some time, there's no doubt about that," head coach Bill O'Brien said.

The Pro Bowl running back suffered a groin injury on Monday evening at practice. O'Brien said the organization had "no idea how much time he'll miss."

In 2014, Foster gained 1,246 yards in 13 games. He averaged 4.8 yards per carry and scored a combined 13 touchdowns on the ground and through the air. Behind him on the depth chart are Alfred Blue, Jonathan Grimes, Chris Polk and Kenny Hilliard.

O'Brien was quick to emphasize that Foster is still getting evaluated. The head coach also said the preparation Foster put in from January through July was impressive.

"I feel bad for him personally," O'Brien said. "He came into this offseason and worked extremely hard."

Foster is also the franchise career leader with 6,309 yards rushing, but O'Brien said the Texans won't spend time moping. He said the organization will look for possible help via free agency and trade.

"As a football team, it is next man up," O'Brien said. "That's the news on Arian as I know it now."

Texans running back Alfred Blue talked about O'Brien's philosophy. "I would say it's an opportunity. Just make the best of it. Even when Arian was there, it was still an opportunity for the second spot. You just have to compete every day. Come out and make the best of the opportunity," Blue said.

The Texans practiced Wednesday morning at the Houston Methodist Training Center, and will fly to Richmond, Virginia in the afternoon. They'll practice there against Washington on Thursday, Friday and Saturday.