*RB Best could return for California* (22) California (4-1) at Arizona (4-2), 10:00 pm EDT TUCSON, Arizona (Ticker) -- California overcame the absence of running Jahvid Best to defeat Arizona State in its last game on October 4. Following the second of their three bye weeks this season, the 22nd-ranked Golden Bears could have their leading rusher back in the lineup Saturday when they visit Arizona in a Pac-10 Conference contest. The versatile Best, who has rushed for 421 yards and four touchdowns, also leads the Football Bowl Subdivision in all-purpose yards per game. Best dislocated his left elbow in a 42-7 victory against Colorado State on September 27. With Best out, Shane Vareen handled the bulk of the running against Arizona State, rushing for 93 yards on 27 carries. That game also marked the return to the starting lineup for California quarterback Nate Longshore, who won his 19th game to move into second on the school's all-time list. He completed 17-of-28 passes for 198 yards and three touchdowns. Longshore did not play in Cal's 35-27 loss at Maryland on September 27, but took over in the third quarter against Colorado State after Kevin Riley was benched. California (4-1, 2-0 Pac-10) enters Saturday's game as the only team without a loss in Pac-10 play, although the Bears have played only two conference contests. The game matches two of the best defenses in the country, as Arizona ranks ninth in the Football Bowl Subdivision (261.5 ypg) and California 25th (290.6 ypg). On the other side of the ball, the Wildcats lead the Pac-10 in scoring (40.2 ppg) with Cal (39.4 ppg) third in the league. However, Arizona (4-2, 2-1) is coming off its first conference defeat, a heartbreaking 24-23 loss to Stanford last week. After the Wildcats had to settle for field goals on a pair of drives inside Stanford's 5-yard line in the fourth quarter, the Cardinal erased a 23-17 deficit on Toby Gerhart's 1-yard TD run with 25 seconds remaining. The Golden Bears have won four of the last five meetings with Arizona - with all the victories coming by at least 18 points - but they dropped a 24-20 decision to the Wildcats the last time the schools played in Tucson in 2006.