Indy-car driver Roberto Guerrero was taken off...

Indy-car driver Roberto Guerrero was taken off the critical list a week after suffering head injuries during tire testing at the Indianapolis Motor Speedway.

Guerrero remains unconscious, but his condition was upgraded from critical but stable to serious because he has begun responding to simple commands. Guerrero has not regained consciousness since Sept. 10, when he was struck in the head by a tire after his race car hit the wall at the speedway.