One of them was considered a sure-fire pick for professional football. The other showed an aptitude for a career as a mortician.

Both ended up as lawyers, working the nondescript, routine cases of hometown law in Virginia: divorces, automobile accidents and minor criminal cases. Theirs have not been legal practices of headlines or professional fame.

Now both are seeking the state's highest legal office, locked fiercely in what is expected to be the most expensive campaign ever for Virginia attorney general. Each is expected to spend in excess of $1 million.

William Ryland (Buster) O'Brien, the 38-year-old Republican whose football career got no further than the taxi squad of three pro teams, eventually returned home to Virginia Beach and set up a general practice that has leaned heavily on minor criminal cases.

Mary Sue Terry, the 37-year-old Democrat who ignored the college aptitude test that pegged her as a potential mortician, turned to the profession in which she scored second best: law. She, too, went home -- to the tiny southwestern Virginia town of Stuart and opened an office alongside the handful of attorneys working in rural Patrick County.

"I wanted to be the lawyers' counterpart of a country doctor," she said.

Even though his Republican running mates call O'Brien one of the best criminal lawyers in the state and Terry's ticket mates call her a brilliant attorney, interviews with lawyers in their home towns indicate both are better known for their political ambitions than their legal careers.

Those colleagues are less effusive, using such descriptions as "good" and "capable" to define the legal skills of each.

"Both have small-town law practices," said University of Virginia political scientist Larry J. Sabato. "I don't think either Terry or O'Brien is a lawyer's lawyer."

Both candidates have been buffeted by allegations from the opposing party questioning their legal abilities. O'Brien has been particularly targeted by many Democrats as well as a number of officials in his own party.

"As a lawyer, I can't say he's carried a heavy weight," said Moody E. Stallings, a Democrat and one of the few Virginia Beach attorneys who will criticize O'Brien publicly. "He's a good ol' boy, but he's got no business being attorney general."

Terry also has her share of detractors. "I know people who didn't seek her out for a lawyer when they were looking," said Patrick County Supervisor Roscoe Epperson, a Republican. He said some county residents dislike her intensely. "But that may have not been because of her skills as a lawyer, but because she's a woman."

O'Brien, as well as many of his Republican and Democratic legal colleagues, says that negative perceptions of him may be more a result of his folksy courtroom style and athletic background than an accurate assessment of his legal skills.

"Buster does come out with the good old boy personality, the 'I'm just a dumb jock,' " said Robert J. Humphreys, deputy commonwealth's attorney for Virginia Beach and a longtime friend. "He suits that to the occasion. Buster did not get where he is by being a dumb jock."

"Many people have a concept of athletes sometimes as being big dumb jocks -- they can lift 400 pounds and can't walk through the door," said O'Brien, who was a star quarterback at Princess Anne High School in Virginia Beach and played football at the University of Notre Dame and the University of Richmond. "I don't think any of those things are characteristic of me."

O'Brien, the first person in his family to graduate from college, said, "I'm not going to tell anybody that I'm the most intelligent person in the world. I think I have a good native intellect."

In the state General Assembly, where Terry has served eight years and O'Brien six years, neither has earned the reputation for the sharply honed legal genius displayed by a number of the other lawyer-legislators who use their courtroom skills to hammer committee witnesses and sway legislative colleagues.

Terry and O'Brien concede that they have put their political careers ahead of their profession, first as members of the House of Delegates and now as candidates. Terry said she has not been in the courtroom since last July and O'Brien quit practicing about a month ago.

Political colleagues in their respective parties say Terry and O'Brien have political ambitions beyond the attorney general's office, which has an $8 million annual budget and a staff of 125 lawyers. Both have been mentioned as potential candidates for governor in future campaigns, a suggestion neither will openly embrace or reject.

"Obviously it can be a capstone to a legal career or a cornerstone to a political career," said Terry of the $56,000-a-year attorney general post.

It is the latter characterization that troubles many attorneys and some politicians.

"The attorney general's office is now a steppingstone to something else," said Phil Clark, who for years was the Democratic political boss of Patrick County, citing the many attorneys general who have run for governor in Virginia. "It demeans the office when it becomes a political implement rather than a legal position."

The most recently elected state attorney general, Democrat Gerald L. Baliles, resigned from the post last month to pursue his campaign for the governorship. Baliles' opponent in that race, Republican Wyatt B. Durrette, was an unsuccessful candidate for attorney general in 1981.

William G. Broaddus, Baliles' former chief deputy, will serve as attorney general until the winner of this year's race assumes office in January.

Earlier this year, O'Brien was criticized harshly by some of his own party officials who accused him of being a "lazy" candidate.

"I was amazed by that," said O'Brien, whose campaign staff says he earned $85,000 in 1984 in his four-partner firm. "I'm not a wealthy guy. I live in a three-bedroom ranch house. My wife does not work. I've had to work fulltime -- that's 50 hours a week -- in my law practice. We have had almost nightly campaign events since January."

In contrast, Terry left her three-partner law office more than a year ago to campaign full time. She has declined to disclose her 1984 income from her law practice. Although she has raised almost twice as much money as O'Brien -- more than $400,000 -- a recent poll showed the two in a virtual dead heat.

While the type of law Terry and O'Brien practice is very similar -- typical Virginia courthouse law -- the courtroom styles of the two are dramatically different.

"You never try a case against him without enjoying yourself," said prosecutor Humphreys. "He'll banter with you. You come away laughing."

"I'd cringe when I see Mary Sue in court," said Patrick County Commonwealth's Attorney Anthony Giorno. "She'd beat you to death with motions. She'd pick on every bit of evidence. I knew when Mary Sue was on the other side, I had my work cut out for me . . . . It was like walking into a buzz saw."

Both O'Brien and Terry used their home town connections to break into the legal profession.

As a high school football star, O'Brien was courted by major collegiate coaches. Notre Dame alumnus and Virginia Beach criminal trial lawyer Richard G. Brydges, a Republican, was instrumental in persuading O'Brien to sign up with his alma mater. Brydges said he also encouraged the young athlete to become a lawyer, because he would always have a job.

After unsuccessful attempts to break into professional football with the Washington Redskins, the San Francisco 49ers and the Ottawa Roughriders, O'Brien received a law degree from The College of William & Mary's Marshall-Wythe School of Law and took Brydges up on an offer to join his firm.

"Dick sort of put me under his wing for the first eight years," O'Brien recalled.

Terry, who as a teen-ager frequently would build county fair booths for local Democratic politicians, was hired as the part-time assistant prosecutor by Commonwealth's Attorney Phil Clark when she graduated from the University of Virginia's law school.

"She was local, she went to law school and she passed the bar," Clark said.

On the campaign trail and in her political brochures, Terry relies strongly on what she calls her experience on both sides of the courtroom table, as a prosecutor as well as a defense attorney.

"The cases were not the type you'd have in some areas," she said. "You'd prosecute people for stealing a ham or stealing an animal. But you would have crimes of violence: rape, robbery, manslaughter. You just didn't have the incidence you have in urban areas."

Outside of her four years as a part-time prosecutor, Terry's practice has not varied significantly from O'Brien's. Both are typical of average general practice law firms: a heavy dose of personal injury lawsuits from automobile accidents, divorce cases, a smattering of real estate dealings and a wide array of small-time criminal cases from burglary to traffic offenses.

Terry describes her most memorable case as the 1977 trial of members of a gypsy band accused of robbing an elderly lady. The court was forced to bring in a United Nations interpreter to translate the Serbian dialect of the gypsies. Moreover, Terry said the gypsies tried to put a hex on her during the trial.

O'Brien said one of his most satisfying cases occurred three years ago when he won a major financial settlement for a woman who was severely injured in an automobile accident. The settlement, which he refused to disclose, was large enough to ensure the woman a comfortable life without working and to pay for her two daughters' expenses, including college.

Such general practice cases may be beneficial to the candidate who wins the attorney general's office, says William D. Dolan III of Arlington, outgoing president of the Virginia Bar Association.

"The attorney general shouldn't rely on a narrow area of expertise," said Dolan. "But they're always going to make somebody unhappy with every opinion. They'll have to be a very good lawyer to stand the heat or there'll be a temptation to try and please the people."