SAUL LOEB/Arizona Daily Wildcat Freshman running back Mike Bell shakes a defender earlier this season against NAU. Bell will make his first start of the season Saturday after an injury sidelined Clarence Farmer for 3-6 weeks.

Before the season even started, the Wildcat football team was on an uphill battle to compete in the Pacific 10 Conference. They were chosen by almost everyone in the nation to finish eighth in the 10-team conference.

After four non-conference games and plenty of injuries to key players, the hill might have gotten even steeper.

UA (3-1) opens up its Pac-10 schedule against the No. 8 Oregon Ducks at 7:24 p.m. on Saturday at Arizona Stadium.

If You Go... Who: No. 8 Oregon against UA Where: Arizona Stadium When: Tomorrow at 7:24 p.m. TV: Fox Sports Net with Steve Physioc and Tom Ramsey Tickets: Individual tickets can be purchased for $7 Oregon Players to watch: Wide receiver Keenan Howry, Linebacker David Moretti UA Players to watch: Running back Mike Bell, Safety Clay Hardt

To make matters worse, the Ducks are currently the only undefeated team in the Pac-10 and are riding a conference-high nine-game winning streak. OU is also coming off a bye week, so they have had an extra week to prepare for the Wildcats.

"(The bye week) is a big advantage going into Pac-10 play," said head coach John Mackovic, who lost his first five Pac-10 games in his first season at the helm last year.

One thing that the Ducks probably weren't planning on was the absence of Arizona's preseason All-American candidate junior running back Clarence Farmer. The Wildcats found out earlier in the week that Farmer would be out for 3-6 weeks with cartilage damage in his knee, an injury he suffered late in the 14-9 win over North Texas. That leaves the Wildcats with redshirt freshman Mike Bell to handle most of UA's rushing duties.

"You can't replace a guy like Clarence Farmer," senior quarterback Jason Johnson said, "but at the same time I have so much confidence in Mike Bell.

"Mike is ready for (the starting running back) responsibility, but like anything else I don't know if anyone can be counted on to be in there every down. We have to be able to spell him."

The factor that could aid a hurting running attack is a solid passing game. Johnson threw for an average of over 400 yards in the first two games of the season, but has struggled a bit in the latter two games.

"(The passing game) has to step it up," Mackovic said. "This is definitely a time when they will have to be front and center."

"We are going to have to throw the ball to win games," Johnson said. "We are still going to need that balanced attack, but I welcome (throwing the ball more)."

The Wildcat offense will also have to deal with the fact that the Oregon rush defense is second in the conference and is allowing only 91.8 rushing yards per game.

The Oregon defense is anchored by senior linebacker David Moretti and junior linebacker Kevin Mitchell. Both are in the top 10 in the Pac-10 in tackles per game, with 8.5 and 8.0, respectively.

"Oregon is the best defense that we have played up to this point. They are so physical up front, they have great linebackers and both of their safeties cover so much ground. Both running and passing will be difficult," Johnson said.

The Wildcats have their own dominant linebacker in senior Lance Briggs, who is second in the Pac-10 in tackles per game (8.8). However, Briggs didn't play much in the second half of the North Texas game and is still listed as questionable for the Oregon game. He has been limited in practice all week.

The Arizona defensive secondary is another area of concern. The week before the Wisconsin game, UA lost junior cornerback Michael Jolivette for an extended period of time and the starter on the other corner, freshman Darrel Brooks, is questionable with back problems. That leaves the coverage duties to junior Gary Love and fifth-year senior David Hinton.

That could make the Ducks throw even more than they already do.

Oregon is lead by junior quarterback Jason Fife, who has been compared to former Oregon quarterback and current NFL starter Joey Harrington. Harrington lit up the Wildcats last season for six touchdowns before he was pulled in the fourth quarter with the Ducks comfortably ahead.

"Any quarterback in Oregon's system will do well," Johnson said. "They are well coached and have so much talent around him, it was just a matter of time (before he was successful)."

One big reason for the success of the Oregon offense this year has been the number of weapons they have on offense. Senior receiver Keenan Howry, junior receiver Samie Parker, and junior running back Onterrio Smith have lead the Ducks to their national ranking and are currently second in the Pac-10 in offensive scoring.

"We need to take the Pac-10 season one game at a time," Johnson said. "We have to worry about Oregon, see how the pieces fall and then just go form there."