TUCSON, Ariz. -- Arizona (No. 18 BCS, No. 20 AP) likely will be without two of its top tailbacks when it plays host to Washington State on Saturday.
"Both would be very questionable for this week," coach Mike Stoops said at his weekly campus news conference on Monday. "Greg is probably more available than Nic."
Grigsby, who is averaging 7.5 yards on his 71 carries, injured his right shoulder against Oregon State on Sept. 26. He was limited in each of the next two games before re-injuring the shoulder against UCLA on Oct. 24.
Nwoko, who has rushed 43 times for 190 yards and three touchdowns, injured his left shoulder against UCLA.
If Grigsby and Nwoko can't play, much of the rushing load would fall to sophomore backup Keola Antolin. He'll face a Washington State defense that ranks 114th out of 120 teams against the run, allowing 220.38 yards per game.
The 5-foot-8, 186-pound Antolin has been sidelined with a sprained ankle this season, but he entered the UCLA game after halftime and rushed 16 times for 77 yards. Antolin had two 100-yard games last season.
Stoops said he likes the way Antolin attacks the line of scrimmage.
"He has great burst and suddenness; that's the thing you notice every time you see him run," Stoops said.
"He gets the ball and then the next thing you know, he is through the line," Stoops said. "He sees things very well. He is quick getting to holes. And he can make people miss. He's hard to get a good shot on."
Antolin, who has 49 carries for 255 yards, likely will be backed up by fourth-stringer Nick Booth, a senior who has 10 rushes.
Stoops said the coaches are looking at true freshman H-back Taimi Tutogi as an option in short yardage or goal line situations, helping with a role that Nwoko often fills. In case more injuries strike, true freshman Daniel Jenkins is preparing to come out of his redshirt.
Arizona's other major injury concern is starting defensive end Brooks Reed, who has missed almost all the Pac-10 season with an ankle injury. Stoops said he would like Reed to play against Washington State (1-7, 0-5) so he'll be ready for a tough closing stretch that includes California (No. 20 BCS, No. 23 AP) on the road, Oregon (No. 8 BCS, No. 7 AP) at home and No. 12 USC on the road.