Arizona RB Grigsby sprains ankle at practice
Posted by ESPN.com's Ted Miller
Grigsby rushed for 1,153 yards and 13 touchdowns a year ago and is one of five running backs in the Pac-10 who eclipsed the 1,000-yard mark in 2008.
His backup, Keola Antolin, is very capable. He rushed for 525 yards and 10 touchdowns, including a breakout performance against California when he rushed for 149 yards and three touchdowns.
Greg Nwoko, a 220-pound redshirt freshman is listed No. 3 on the depth chart.