But when Davis learned Monday morning that Klein, the former Chargers owner, had died of a heart attack in San Diego at 69, he could only speak of the relative insignificance of their professional and personal differences.
"It's just tragic," Davis said. "We're not talking about the playing field, we're talking about the game of life, and that's a little different."
Word of Klein's death filtered quickly Monday through the meeting rooms and hallways of the Orlando hotel where NFL owners are conducting their annual meetings. He was remembered by his former fellow owners as a loyal public supporter of league policy and a pioneer of the move into big-money television contracts.
"He brought a very keen, aggressive business sense to the league, and he was a team player," said Wellington Mara, owner of the New York Giants. "He was a rugged individual, but he made his decisions based on what is best for the league."
One of the first to hear of Klein's death was George Pernicano, a minority stockholder of the Chargers since 1961. Pernicano bought into the team shortly after it moved to San Diego and has kept a financial interest through the majority ownerships of Barron Hilton, Klein and Alex Spanos. He learned of Klein's death in an early-morning telephone call, but two hours later he stood outside the owners' meeting room still stunned.
"Until I get home I can't even believe it myself," Pernicano said. "We had fun; we had a lot of fun together."
News of Klein's death came only hours before Davis called a news conference to announce he was returning the Raiders to Oakland no later than the 1992 season. Davis' decision was a final ironic twist to the bitter professional feud Davis and Klein waged over much of the past 10 years.
They were on the opposite side twice in suits over the move of the Raiders to Los Angeles in 1982. Klein suffered his first heart attack in 1981, while testifying in defense of the NFL in an antitrust suit brought by Davis involving the move.
Klein later sued Davis for malicious prosecution in connection with the suit. A San Diego Superior Court jury sided with Klein and awarded him $10 million in damages in 1987. But the award and judgment were overturned on appeal.
"When a person dies, that is a different ballgame," Davis said. "You're not adversaries in anything when it comes to life or death.
"I know this. It will make a lot of owners and lot of people do a lot of thinking over the next 48 hours when somebody like that passes away at a very young age."
Most owners learned of Klein's death when they came downstairs for a morning general session. Ralph Wilson, owner of the Buffalo Bills, said he knew Klein had been in fragile health because of his heart condition. He said they discussed it in their last meeting in November in Keeneland, Ky., where Klein sold his stable of thoroughbred horses at auction. He said Klein told him he was selling the horses for health reasons.
Wilson said he was sorry to see Klein have to leave horse racing because of his impressive success in only a few years in the sport. Klein's biggest horse racing victory came in 1988, when Winning Colors won the Kentucky Derby.
"He was the most successful horse owner in this century in a short period of time," Wilson said.
Their interest in football and horse racing made them friends in the small fraternity of NFL owners. Their rapport was strong enough that Wilson had no fears of kidding Klein about his casual style of dress. He warmly recalled a dinner engagement several years ago at a Denver hotel in which Klein was refused seating because he would not wear a tie.
"They wouldn't serve us dinner, I'll never forget that," Wilson said. "I said, 'Come on, wear a tie so we can eat.' But he wouldn't do it, and we went somewhere else."
Wilson was one of several owners who shared Klein's love of horse racing. Since Klein sold the Chargers to Spanos in 1984, they would most frequently meet at the track.
Not all of them profited they way Klein did. Asked if he had ever bet and won on Klein's horses, Mara smiled.
"Yes," he replied, "but they were usually short prices."
But while Klein was respected for his later success in horse racing, his former NFL colleagues said he will be best remembered for his appealing personal style and his work in helping land multimillion dollar television contracts.
His knowledge of the entertainment field built from his years in the movie distribution business made for his selection to the league's television committee.
"He was a very persuasive man, able to sell his point of view with far greater ease than others," said Cleveland owner Art Modell, who served with Klein on the committee. "He was a decent man, a fierce competitor. I don't care if it was running a horse, fielding a football team or helping negotiate a television contract. For that, he will be sorely missed, as a person and as a friend."