Thirty-six days ago he signed a pro football contract, leaving Greg Foster and track and field suffocating in the dust somewhere near the fifth hurdle.

These days, Renaldo Nehemiah is no longer a blur. On the training field of his new team, the San Francisco 49ers, the strides are shorter and the days are longer.

As he sat on a bench--a place he hopes to avoid once the National Football League season begins--Nehemiah looked sleek and strong.

He is 6 feet 1 and weighs 177 pounds. "That's bigger than a lot of NFL receivers," said Nehemiah, 23, who has not played football since he was a 5-foot-10, 155-pound quarterback in high school six years ago.

He is one world champion joining another. He has not forgotten his world record of 12.93 seconds in the 110-meter high hurdles in Zurich last year. "I was clockwork," he says.

He is also a novice. The sign above his locker reads "No. 83, rookie." It's been a long time since Renaldo Nehemiah has been a rookie.

Consequently, after enduring four weeks of individual tutoring with 49er coaches and three days of minicamp with his new teammates, Nehemiah--the wide receiver--admits there have been pains and pressures.

"I feel the pressure because there is so much of it. When I go onto the field I see the TV cameras rolling, the people watching. There are some players and other people who are looking for me not to cut the cake. I have become a sensitive subject. That's why I agreed with the coaches to cut down on my interviews. There is envy because some people here don't understand me yet."

He signed a four-year contract, only the first year guaranteed, for an estimated $100,000 a year. He also received a guaranteed signing bonus.

On the field there are no guarantees. "I took about 150-200 passes a day, six days a week from (quarterback coach) Sam Wyche and some from Joe Montana for a month straight. I've dropped some passes, easy ones. It's bothered me. It's like I'm studying for an exam, know the material and still get an F. But I think I have done well. Coach (Bill) Walsh says I'm ahead of the game."

In his plush office that overlooks the 49er training field, Walsh talked about the luxury named Nehemiah.

"Everything we have expected of Renaldo, he's surpassed. He's not rigid or mechanical. He's supple, flexible. We have three good receivers in Dwight Clark, Freddie Solomon and Mike Wilson. At some point this will haunt Renaldo, because he wants to be the best.

"I won't say he'll start, but he'll play a good deal. It's a highly skilled game that will take time for him to learn. His day will come."

Nehemiah, confident and cool, thumped his forefinger twice on the table before him and said, "I will be ready to contribute by game time, first game."

A track and field runner who attempts to move to the NFL without college football experience has plenty of recent history to review.

Players like Bob Hayes and more recently Curtis Dickey and Johnny (Lam) Jones played college football in addition to participating in track and field.

As Nehemiah attempts to embrace the NFL, he will also attempt to avoid the ghosts of Tommie Smith, John Carlos, Jimmy Hines and Frank Budd. Between them, they have three Olympic medals and several former world records. They also have the grand total of 11 NFL receptions.

Smith, 200-meter gold medalist in 1968, played with the Cincinnati Bengals from 1969-71, mostly on the now-defunct taxi squad. Then he headed north to Canada.

"I actually had three problems with the transition to football: transferring my speed into 90-degree angles, using my hands and learning the plays," said Smith, 36, now track coach at Santa Monica City College.

"After being the world's greatest, it was tough going to the taxi squad. . . as for the contact, at least I knew the other guy was in misery, too. My worst injury was a separated shoulder when two Raider defensive backs slammed into me."

Carlos, 200-meter bronze medalist in '68, was on the roster of the Philadelphia Eagles in 1969. An injury in spring camp, however, ended his season before the Eagles started theirs. "In camp, I kept outrunning our quarterback's (Norm Snead's) arm," said Carlos, 36, now with the Los Angeles Olympic Organizing Committee.

In that spring camp, Carlos dived for a pass thrown out of his reach and tore knee ligaments. "I wasn't used to the AstroTurf. I didn't recover for six months. When I came back, they had Harold Carmichael. That was that," said Carlos, who never again played in the NFL.

Hines, 100-meter gold medalist in '68, failed to make the Miami Dolphins in '69 and retired.

"In my first (practice) game against the Raiders, I returned a kickoff. I was hit and lost consciousness for a few seconds. When I woke up I realized I had fumbled but at least my teammates had the ball," said Hines, 34, now with the Austin, Tex., human services department. "I played pretty well in the other practice games but I never got in a regular-season game. I think the coaches rushed me."

Budd, fifth in the 100 meters in the 1960 Olympics, played with the Eagles and Redskins in 1962-63.

Budd, who caught 10 NFL passes, including a touchdown pass from Sonny Jurgensen when he played for the Eagles, said, "My problem was that I tried to catch the ball with only one arm. It took two years for the coaches to figure out what I was doing wrong," said Budd, 42, now with the Delaware Valley Regional Planning Commission.

In two years, Frank Budd's NFL career was over.

Renaldo Nehemiah knows about the track-to-football history.

"I've displayed heart. My ego will not allow me to assume I'll fail at something. I have everything to gain and nothing to lose here. Maybe the admiration, the glamor and the glory will go down some."

Maybe the pain in Nehemiah's right thigh will go down some, too. Nehemiah injured the quadricep muscle in camp while diving for a ball that was slightly overthrown by quarterback Guy Benjamin. He made the catch, somersaulting to the applause of teammates.

Said Benjamin, the 49ers' reserve quarterback, "The discouraging thing is when you underthrow him and Renaldo returns to the huddle saying he wasn't even running full speed."

Some wonder if he can take a hit. Nehemiah does not.

"The kind of hits people talk about even the best in the league can't take. The natural hitting I can deal with. If you're talking about the guy lunging and smacking me in the face, yeah, I'll get hurt," Nehemiah said.

Wyche, the quarterback coach, said, "Skeets will have to be hurt pretty bad to come out. He's muscular but not too tightly wound."

Nehemiah said of the injury, "No, I never did have anything like it in track and field."

Tommie Smith, John Carlos, Jimmy Hines and Frank Budd are names Nehemiah does not want to hear. But he might like to hear what they say about him.

Says Smith: "Nehemiah does not come from a Cinderella background. He may put his shoulder pads on backwards once. But he'll make it."

Says Carlos: "He is unique. He's the one to do it."

Says Hines: "He's very muscular. If they give him the time and the coaching help, he'll make it."

Says Budd: "He's been somewhat preconditioned running hurdles. He'll make it."