NAPA — Michael Bush is tired of watching after spending nearly two years on the sideline while his teammates got to play football.

Bush has not played in any game since breaking his right leg in the season opener of his final college season at Louisville in 2006. He missed the rest of that college season and all of his rookie campaign with the Oakland Raiders in the NFL, putting special meaning on his exhibition opener against San Francisco on Friday night.

“I didn’t think it’d be this long,” Bush said. “I was told six months, seven months. It turned out to be two years now. So I’m just ready to get out there and get it going again.”

Bush was considered one of the top running backs in the country before breaking his leg against Kentucky on Sept. 3, 2006. He was coming off a junior season in which he ran for 1,143 yards and an NCAA-leading 23 touchdowns, and was being projected as a possible first-round pick in the 2007 NFL draft.

Instead he began a long rehabilitation process that has taken far longer than he expected. The leg didn’t heal quickly enough from the original operation, leading to a second surgery about a month before the draft. That helped lead to Bush’s slide into the fourth round, where the Raiders were happy to take a chance on a talented player.

He originally hoped to be ready for training camp last year but instead started off on the physically unable to perform list, where he remained once the season started.

Bush said he felt ready to return a few weeks into the season but never got the chance as the Raiders eventually placed him on injured reserve because they had too many other running backs in Justin Fargas, LaMont Jordan and Dominic Rhodes.

Bush got to practice with his teammates for a few weeks last year before being placed on injured reserve. He admitted it was tough watching his teammates play football while he could only work on back fields, but hopes it pays off this season.

“It was like I was training, basically, to one day get on the field,” he said. “There weren’t any low points. I was out there basically focusing on my conditioning, just trying to get right in every aspect of the game as far as quick speed. And still I was in the meeting rooms as well. Just being in locker room with the guys as well was pretty cool as well.”

Bush is now part of a crowded backfield in Oakland, which includes a 1,000-yard rusher in Fargas and heralded rookie Darren McFadden. Bush believes he has shown the coaches he is 100 percent by the way he can run and cut in drills.

He got coach Lane Kiffin especially excited in a drill early in training camp, when he lowered his shoulders into the pile in a full-pad goal-line drill. Kiffin wants to see more of the same in the game against the 49ers on Friday as he hopes that Bush can be the short-yardage back this season.

“He’s 246 pounds, don’t run like a 200 pounder, and see what we have,” Kiffin said. “We got a glimpse of him in the goal line situation, and hopefully that’s who he is and that’s who he needs to be to be able to play for us. He’s the one big guy we have, and if he can do what we hope he can do I think we’re in a real good position there.

Bush got singled out for praise by Kiffin after Wednesday’s practice for picking up Gibril Wilson on a blitz and running physical.

Bush knows he will need to show more of those skills in order to get on the field this season.

“That’s not a problem for me. I can be a bruiser if I need to be. I just basically play the game, I’ve been playing it for a long time. I’ll drop my shoulders if I need to, if not, I won’t,” he said. “In goal line and stuff like that, you need to run like a big guy. You need, third and short yardage, you need to lean forward and get your head down. That’s what you need to do as a running back, big or small.”