Virtually out of nowhere, Oklahoma's Billy Sims has emerged as the leading candidate for the Heisman Trophy.

The attention hasn't fazed him in the least.

"My goal before the season was just to stay healthy and play consistent each game," said Sims, who is the nation's leading rusher. "Winning the Heisman never entered my mind. The national championship is far more important than that, anyway. The Heisman involves too much politicking. The national championship is settled on the field."

But the 6-foot, 205 pound Sims already may have the trophy locked up and ready for shipment back home to Hooks, Tex.

When the No. 1-ranked Sooners face No. 4 Nebraska in Lincoin Saturday before a national television audience in their annual Big Eight showdown, Sims will be going for an NCAA-record fourth straight 200-yard rushing game.

He is averaging 155.2 yards a game for the 9-0 Sooners, gaining a whopping 7.9 yards a carry, and is fifth in the country in scoring, having gotten at least one touchdown in every game this season.

Sims has been hampered by injuries most of his college career, with a broken shoulder in 1976 and ankle problems last year. He would be a senior this season but because he played in only one game in 1976 was given another year of eligibilty.

Sims, who has rushed for 1,397 yards this reason, started with a modest 107 against Stanford. He followed with 114 yards against West Virginia in only eight carries. Then, against Rice, he carried eight times and gained 33 yards as Oklahoma won, 667.

Against Missouri, Sims started carrying the ball more. He lugged it 14 times for 166 yards and four touchdowns and 25 times for 131 yards and two scores against Texas the next week.

Next came a 192-yard day in a 17-16 victory over Kansas in Oklahoma's closest game this season.

Then he started his string of 200 yard games. He got 231 yards against Iowa State, 202 against Kansas State and 221 against Colorado last Saturday. That is 654 yards in three games against tough competition.

"I don't think there's any doubt that he's amazing," said Oklahoma Coach Barry Switzer. "He hardly played at all against Rice or West Virginia. If he had, he would have had a couple more 200-yard games against those amateurs. He also had a lot of long runs called back this year because of penalties a 73-yarder and a 30-yarder that I can think of offhand."

Sims has an ideal blend of speed, quickness and strength. He runs a 4.4 40-yard dash and cannot be arm-tackled.

The only Sooner to win the Heisman in the last 25 years is running back Steve Owens, who did it in 1969. Since then, the most noted Oklahoma backs, before Sims, have been Joe Washington, Greg Pruittt, and Eivis Peacock. Washington was the last Oklahoma player to rush for 1,000 yards in a seaon, doing it in 1974.

Pruitt holds the single-season Oklahoma rushing record with 1.665 yards and an NCAA record 9.4 yards a carry, set in 1971.

"Billy is quicker than Washington and faster than Pruitt," said Switzer, "and stronger than both of them put together."

Sims gets most of his yards from pitches as a halfback running out of the wishbone offense.

To get even more out of him and take better advantage of his skills, Switzer installed an I-formation this season, with Sims at tailback.

The Sooners run out of that formation only about 25 percent of the time, but just having it makes Sims much more of a threat.

Running from the I, Sims has the entire field open to him instead of being confined to a limited area as he is when he runs from the wishbone.

"I knew all along he would be a great back," Switzer said, "so we had to come up with a way to get him the ball more.

He's still only carrying the ball about 19 times a game. There are a lot of backs who could gain the yards he has, but it would take them twice as many carries. Look at his per-carry average - 79 that's unreal and that's what makes Billy Sims the best running back in the country."

Sim's chief competition for the Heisman probably will come from four quarterbacks - Rick Leach of Micihigan, Chuck Fusina of Penn State, Jack Thompson of Washington State and Steve Dils of Stanford - and from running backs Charles Alexander of LSU and Charles White of Southern California.

None, however, has been as consistently spectacular as Sims.

Does he think he can get a fourth straight 200-yard game against Nebraska Saturday?

"I expect a big game every game," Sims said. "I don't shoot for goals, though. I want as many yards as I can get every time I carry the ball and I want as many yards as I can get every game, whether it's against Rice, Texas or Nebraska."