For 55 historic minutes last week, 23-year-old Sebastian Coe of Britain was the only runner ever to hold four world records at the same time.

But less than an hour after he added a 1,000 meters record (2:13.40) to the world marks he set for 800 meters, 1,500 meters and the mile last summer, Coe watched his 24-year-old British rival, Steve Ovett, take away one of them by shaving one-fifth of a second off Coe's mile mark on the same fast Bislett Stadium track in Oslo. Coe's time was 3:48.8.

Coe came down from the stadium stands to shake Ovett's hand. "Congratulations," Coe told Ovett. "I enjoyed your race."

"Sorry, I didn't see yours," Ovett answered. "I was warming up."

The brief conversation and their record-breaking one-upmanship on the warm, still evening, while once again avoiding each other in the same race, were typical of the rivalry that has grown between two young men from the same small isle who happen to be the best middle distance runners in the world.

"I have no doubt they are the two finest middle distance runners I've ever seen, and that goes back to 1936," said Christopher Brasher, British Olympic gold medal winner who is now a leading track and field journalist here.

"When they meet in the metric mile (1,500 meters) at the Olympics in Moscow, it should be the world's greatest race since John Landy and Roger Bannister in the Miracle Mile race in 1954."

Before they meet in both the 800 meters and 1,500 meters in Moscow, Coe and Ovett will have raced against each other only once. It was in the 800-meter final at the European Championships in Prague, in September 1978. While they exhausted themselves trying to beat each other, battling for the lead down the stretch, Olaf beyer of East Germany kicked past them and won the race.

Since then, each has avoided a number of opportunities to race against the other except the confrontation for the Olympics. They also seem to avoid even meeting each other off the track. At a party for the competitors after their record-breaking runs in Oslo, they sat on opposite sides of the room, each with his own cluster of friends, and never spoke to each other.

Some see in this a feud between two uniquely brilliant runners who had the bad luck to mature at precisely the same time in the same country, each forced to share the world stage with the other and only one likely in the end to be judged the greatest middle distance man of his time.

In a charateristically terse postrace comment to reporters in Oslo, Ovett said, "One of my big goals this season was to take this world record from Coe. It tasted terrific."

Coe was just as characteristically expansive and magnanimous. "Records are immaterial and I have always expected any of mine to be broken because they can't last forever," he said in Scandinavia. "Whoever holds them does not matter when it comes to the Olympics because a lot of world record-holders have not succeeded there in the past. But I intend to end the season with as many world records as possible if I am able."

As for his rivalry with Ovett, Coe said last summer after setting his first three world records and suddenly overtaking Ovett as Britain's top running star, "It's crazy to concentrate on one opponent. Look what happened in Prague. Steve and I thought the gold and silver (inm the European championships) were between us, and both got stuffed by the East German. I'll never let that happen again."

"There's no feud," said Brasher, who has followed the two runner's exploits and enjoyed unusual access to them. "It's just rivalry.It's natural to try to prove you're the fastest in the world and try to beat the other's records."

"Rivalry must exist between two people who are the fastest in the world," said David Shaw, secretary of the British Amateur Athletic Board. "It is inevitable when they live and race in the same era. But I don't think there is any great personal animosity between them. I don't think they know each other well enough for that."

Both he and Brasher also pointed out how the two young runners could not be more different from each other -- both on and off the track.

Coe, only 5 feet 9, barely 130 pounds, and softly, boyishly handsome, is a speedy front-runner who races middle distances like sprints, breaking in front early and running away from the pack. He is what we Americans call a well-rounded person, who devotes as much time to college studies and worldly pursuits as he does to training. Opponents and their coaches are astonished that he runs as little as 50 to 70 miles a week.

Ovett, an almost stocky 6 feet and 154 pounds, has a rough face that appears many years older. He is a dogged, come-from-behind runner with a feared finishing kick, who punishes himself by running 160 or more miles each week up and down the hills and along the beaches around his home in Brighton, a seaside resort on England's southern coast. He has raced at every distance from 200 meters to 13 miles.

But perhaps most important to the growing public dimensiion of their rivalry, Coe is open, outgoing, charismatic -- the ideal media personality. Although he seldom consents to long interviews that might interfere with his training or private life, he is available long after each race for another question from reporters, photo opportunity or autograph request, especially from youngsters. Around Sheffield, where he lives in England's industrial midlands, he is easily accessible as just plain "Seb" to adoring townspeople, the model athlete that every parent wants their child to emulate.

Ovett, on the other hand, is the classic lonely long distance runner. Shy, blunt, easily annoyed, especially by the insistent demands of celebrity, he is almost inaccessible to reporters and turns down nearly all invitations to banquets and ceremonies, even a recent one at Buckingham Palace.

Coe was always ready to race in Moscow as long as the British government or athletic officials did not take legal steps to force a boycott of the Olympics after the invasion of Afghanistan, and he has argued his position forcefully whenever asked. But Ovett infuriated British athletic officials by waiting until the last minute to make up his mind, and has refused to discuss publicly his misgivings about participating in the Moscow Games.

Ovett spends almost all his time training, eating and sleeping, running morning, noon and night. Coe told Brasher that he once tried Ovett's regimen for a day because, "I've always been genuinely interested in how Ovett can train in the morning and then go back to bed until midday, and then wake up and do another run and then sleep all afternoon, wake up in the evening in time for another session, this time on the track, and then go home for his meal -- and so to bed."

Coe didn't like it. "For one day I was a full-time athlete," he said. "Now I don't wish to deride that approach. Steve is not a mindless moron. It is simply that there are horses for courses and that is not my course."

Although they have nothing else in common," Brasher added, "they do both come from very close-knit families." Each has a parent deeply involved in his running career.

Coe's father Peter, an engineer who is a production director for the Sheffield Cutlery Factory, is also his son's coach. After studying everything he could find about the theories of well-known coasches and trainers, he designs his son's training regimen himself and maps out each year's racing schedule, goals to be met and records to be set. He long ago wrote down, and keeps secret, the time he believes Coe must beat to win the metric mile in Moscow.

Ovett has a professional coach, but his mother, Gay, who owns a cafe in Brighton (his father also works in the food business), is his manager, secretary and protector. If possible, Ovett is even more devoted to his family than Coe and often waves to them from the track in the last few yards of a winning race, a gesture that has sometimes been mistaken for arrogant showboating. But during last week's mile in Oslo, when literally every fifth of a second counted in his race to break Coe's world record, he did not break stride to wave.

It may be that it has simply been especially painful for Ovett to have to move over for Coe after several years of dominance as Britain's brightest young running star. Since he first broke the four-minute mile barrier in 1974, he had all the headlines. One expert journalistic assessment made just a year ago considered Ovett to be "Britain's main hope for a precious Olympic gold medal."

Then Coe came from out of nowhere late last summer to set three world records in 41 days and become the new golden boy of Britain.

Brasher thinks it's a shame that people see primaritly a rivalry rather than a rare triumph for Britain in its declining years to have such riches. He notes that both runners could win gold in Moscow, Coe with his flashing sprinter's speed in the 800 meters and Ovett in the 1,500 meters with his gritty determination and finishing kick.

But for Coe and Ovett, that would not settle the overriding question of which is the world's greatest middle distance runner.