Pressure is something Wilbur Jackson became used to a long time ago. He had to in order to survive.

In the early 1970s, he was the first black football player at the University of Alabama, hand-picked by Bear Bryant to break the color line. He was also strong and fast, and could catch the football, and he always put out 100 percent.

Jackson paved the way for many other blacks to star at Alabama. He downplayed his role in the integration of the football team and doesn't particularly feel comfortable talking about its enormous significance. For if Jackson had failed, the road might have been tougher for those who followed him.

Wilbur Jackson hasn't changed much in 10 years.

He is still on a hot seat. Now, he is the man the Redskins are hoping can take the place of the retired John Riggins, one of the most productive and popular Redskins.

The Alabama experience didn't faze Jackson very much and neither does the Redskin situation, he says.

"I've certainly been in pressure situations before," said Jackson, who was obtained from the San Francisco 49ers for two second-round draft choices a week and a half ago. "The situations are a little similar in that a lot is expected of you and having gone through one may help you get through the other.

"Because of my nature, the Alabama experience really didn't bother me that much. I never thought about the pressure. I felt comfortable then and I feel comfortable here, too.

"I'm here to do a job, not just to replace someone. I'm just going to try and do my best every day. If I do that, then I'll be satisfied. When a team gives up two high draft choices to get you, it makes you feel good and you want to do your best to show that you are worth it."

When the Redskins were convinced Riggins wasn't going to return this season, they knew they had to find a proven NFL replacement. Clarence Harmon, who has been the No. 1 fullback since Riggins left camp, and who most likely will start Monday night against the Dallas Cowboys in the season opener at RFK Stadium, is not a power running, workhorse-type player and the Redskins would rather use him mainly in special situations.

The only starting fullback they could meet the asking price for was Jackson.

The 6-foot-1, 219-pound Jackson is not considered a true power runner, although he is probably a better inside runner than Harmon. He is quicker and faster than Riggins and a better pass receiver, but whether or not he can get the tough third-down yards Riggins did is unknown. Jackson's strength, much like Harmon's, is in catching passes and keeping the defense off-balance with his versatility.

Jackson rushed for only 375 yards as a 49er last year, but he caught 53 passes for 422 yards.

By comparison, the leading Redskin receiver last season, Danny Buggs, caught 46 passes. Harmon was the leading receiver among the backs with 32 catches for 434 yards.

The development of rookie Rickey Claitt, the leading Redskin rusher in the preseason, also has taken some pressure off Jackson. He now won't have to perform like a miracle worker and shoulder the responsibility of replacing Riggins by himself.

Coach Jack Pardee is impressed with what he has seen of Jackson and says he is exactly what he felt he would be when the Redskins acquired him.

"He's doing real good," Pardee said after yesterday's first hard workout of the week in preparation for Dallas. "He doesn't catch your eye in practice the way he does in a game because in practice, he runs more straight up. When it's for real, he explodes. That's why I'm glad we had a chance to use him in the Tampa game."

Jackson carried six times for 16 yards and caught three passes for 21 yards in that game.

As he has done almost daily, Pardee continued to sing the praises of Claitt. "He could be our best fullback," Pardee said of the hard-running rookie free agent from Bethune-Cookman. "He is more like Riggins than Jackson. We plan on using all three of our fullbacks, anyway."

As much as both Jackson and Pardee try to downplay the importance of Jackson to the team, it nevertheless is obvious that Jackson will have to perform well if the Redskins are to overcome the loss of Riggins. They paid what they feel is a very high price for him and they expect big returns.

Jackson sees himself as just one of a stable of good backs, "each capable of coming through if someone is having a bad game.

"Everyone wants to be a full-time player and start every game, but the game is specialized. You do what you can to help."

Jackson gained 780 yards in 1977 and them missed the 1978 season with torn knee ligaments.

"They weren't completely torn though," he said, "so surgery wasn't required required." Jackson was in a cast for three months and then started on a rehabilitation program. He says the knee is fine and hasn't bothered him at all.

Jackson was a halfback at Alabama and played that position his first two years with the 49ers before being switched to fullback.

Of his 53 pass receptions last season, half were short dump passes in the flat or safety-valve plays, but the other half were downfield patterns in which he was the primary receiver.

"The passing game in San Francisco was complicated one, but they have a real complicated system here," Jackson said. "My running is okay but I'm still trying to get the passing game down.

"The biggest difference in coming from a team like the 49ers to one like the Redskins is in attitude," he added.

"This team knows it will be in the playoffs. It's almost taken for granted. They're looking for more than just getting in, too. They want the Super Bowl. In San Francisco, there never was even any talk about the playoffs."