The Detroit Lions took another hit on Thursday during joint practice with the Houston Texans. According to team reporter Tim Twentyman, running back Sione Vaki left the field with an undisclosed injury.

Vaki, now entering his second NFL season, had been expected to build on a promising rookie year, during which his primary responsibility came on special teams, where he earned valuable snaps. His exit from practice came on the same day starting center Graham Glasgow was forced out with an injury (click here for more on that), raising fresh concerns for Detroit’s depth on offense.

Details on Vaki’s condition have not yet been released, but the Lions will be hoping it’s only a minor setback as they prepare for the preseason. Losing a young, multi-purpose weapon like Vaki for any stretch of time would be a tough blow.