LINCOLN, Neb. (AP) -Cody Green was a man with a plan.

Knowing Nebraska starting quarterback Joe Ganz would leave after last season, Green chose to graduate from high school last December so he could start college in January and be able to participate in spring practice.

A week after supplanting Zac Lee as the starter, Green is preparing to face 20th-ranked Oklahoma (5-3, 3-1) Saturday in a game that could go a long way in determining the fate of the Cornhuskers (5-3, 2-2) in the Big 12 North.

Green's career, obviously, is progressing just as he had hoped.

``I knew I could have a chance to come here and compete,'' Green said Tuesday. ``With Joe leaving, there was an open spot. It was anyone's for the taking, so I did it.''

Lee and Patrick Witt were supposed to be the front-runners to succeed the record-setting Ganz. But Witt transferred before spring practice, allowing Green to get a longer look from the coaching staff.

Lee won the job in preseason practice, but he lost it after the offense went stagnant in back-to-back losses to Texas Tech and Iowa State.

Looking for a spark, coach Bo Pelini started Green against Baylor last week. Green completed 12 of 21 passes for 128 yards and ran eight times for 43 yards in a 20-10 victory.

There was plenty of good and bad in Green's play. He led a scoring drive on his first series, and later he hit Niles Paul on a 45-yard pass play to set up Nebraska's only touchdown. But he also lost a fumble and was intercepted.

Pelini said he liked the way his young quarterback managed the offense and showed poise.

``He's a perfectionist,'' Pelini said. ``There is a lot to learn any time you walk on the field. Obviously, it's more magnified being his first start. You hope he gets better because of all the things he learned and from that experience.''

Had Green taken the traditional college route and waited until the summer to move to Lincoln, he probably wouldn't have been prepared to be the starter this soon.

``Just trying to learn this offense as a quarterback really takes a while,'' Green said. ``And it really took me all the way until halfway through fall camp until things started clicking for me. That's with me being here from January on, to learn the ins and outs of things. If I would have come here in the summer, I think I would be redshirting.''

Instead, he's getting ready to play one of Nebraska's biggest games of the season against one of the nation's best defenses. If the Huskers are going to have a chance to win, they are going to have to be able to run the ball.

And running is an area where the 6-foot-4, 220-pound Green holds a big advantage over Lee.

Green ran with great success at Dayton (Texas) High, and Oklahoma expects to see plenty of running plays designed for him.

``He's a great athlete, a big guy,'' Sooners cornerback Dominique Franks said. ``If we see him, we know that he's going to try to get out of the pocket a lot. He uses his feet and just tries to make plays on the perimeter with him running or scrambling out and trying to find the open receiver.''

Green said he expects the Sooners will try to take advantage of his inexperience.

``That's really what any defensive coordinator would do, try to bring the house on me, change things up and show me things I haven't seen on tape before,'' Green said.

With 85,000 Husker fans eagerly anticipating Green's first start at home, he might feel more pressure this week than he did against Baylor.

For a road game, it was one of the friendliest environments a visiting player could want. There were only 31,702 fans on hand, many of them wearing Nebraska colors. Green said he had 100 family and friends to cheer him, including three of his high school football coaches who made the three-hour drive from Dayton.

Green said he was hard on himself as he watched film Sunday.

Those old coaches, however, were even harder on him. His old offensive coordinator admonished him to hold onto the ball and reminded him that his fumble was his first in two or three years.

His old head coach called him Saturday night and told him he ``choked'' in the second half, when Nebraska was held scoreless, but that he did a pretty good job overall.

``He called me back the next day and said he reviewed the film,'' Green said, breaking into a smile. ``He said, 'It wasn't that bad. You can do better.' Then he hung up on me.'''

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AP Sports Writer Jeff Latzke in Norman, Okla., contributed to this story.Copyright © 2005 The Associated Press. All rights reserved. The information contained in the AP News report may not be published, broadcast, rewritten or redistributed without the prior written authority of The Associated Press.