TUCSON, Ariz. (AP) - The up-tempo offense that made Arizona so tough to stop the first three games is wearing the Wildcats down.

Arizona is averaging 88 plays per game, second nationally to Marshall, and doesn't have much depth, particularly on defense. That means the starters and key backups have been on the field perhaps longer than any players in the country.

The extra time on the field has worn the Wildcats down and led to injuries, particularly the past two weeks in losses to the Oregon schools.

It doesn't get any easier for Arizona this week, either. Up next is a road game against No. 18 Stanford, one of the biggest and most physical teams in the country.