*USC takes on improved Arizona* (4) Southern California (5-1) at Arizona (5-2), 10:15 pm EDT TUCSON, Arizona (Ticker) -- After laying waste to Washington State, Southern California won't have things as easy in the desert. Fresh off its largest shutout win in 77 years, the fourth-ranked Trojans visit much-improved Arizona on Saturday in a Pac-10 Conference clash. USC (4-0, 5-1 Pac-10) blasted Washington State, 69-0, last week, its most lopsided victory in a shutout since beating Montana by the same score in 1931. Mark Sanchez became the first Trojans' quarterback to throw five touchdown passes in a half as USC built a 41-0 lead at the intermission. While the Trojans scored early and often, they also posted their second straight shutout. USC's defense may get overlooked because of the weapons on offense, but it leads the Football Bowl Subdivision in fewest points allowed (7.8 points per game). The Trojans, who have scored 138 unanswered points, have not posted three straight shutouts since 1947. "We wanted to find that level of focus that we really hadn't had yet," USC coach Pete Carroll said. "Knowing that we've got enormous games coming up down the schedule on the road, I wanted to see that we could capture it." The first test comes against an Arizona team that seems to have turned around its season. The Wildcats (5-2, 3-1) defeated previously-No. 22 California, 42-27, last week to move into a four-way tie atop the Pac-10 Conference. Arizona rallied from a 24-14 halftime deficit to improve to 5-2 for the first time since 2000, also the last time they were 3-1 in conference play. Freshman Keola Antolin rushed for 149 yards and three touchdowns for the Wildcats, who did not look like the team that was coming off a 24-23 loss to Stanford and also fell to New Mexico earlier in the season. USC has won six straight against Arizona, including its last three trips to Tucson. Last season, the Trojans had to rally for 10 unanswered points in the fourth quarter to hold off the Wildcats, 20-13. It was the first game after USC suffered a stunning 24-23 defeat to Stanford as a six-touchdown favorite.