Keep this in mind: Through the first three weeks, a top five team has lost in each week.
Week One - No. 3 Oklahoma lost to BYU
Week Two - No. 5 Oklahoma State lost to Houston
Week Three - No. 3 USC lost to Washington
Which top five team might be upset this week?
Week Four is the start of the Big 10 conference season, along with many other conference matchups.
Iowa travels to Happy Valley, where the Nittany Lions are looking to avenge last year's loss and stay on track for a national championship.
USC also looks to rebound from another stunning loss to a second level Pac-10 team.