Joe Morgan waited a long time to become a major league manager. He may have the job only a short time.

Morgan, 57, was named interim manager of the struggling Boston Red Sox Thursday, replacing the fired John McNamara. Boston General Manager Lou Gorman said he would begin an immediate search for a more permanent successor.The upheaval resulted from the team's lackluster performance during a season in which many picked them to win the American League East. Instead, they were 43-42, tied for fourth place and nine games behind division-leading Detroit when McNamara was let go Thursday after 31/2 seasons at the helm.

He was fired 1 1/2 seasons after he managed the Red Sox to within one game of winning the 1986 World Series. But the New York Mets won the sixth game with a two-out rally in the 10th inning and captured the title in Game 7.

The Red Sox have struggled since. They finished fifth in the AL East with a 78-84 record last season and had lost six of their last 10 games under McNamara, 56.

"A manager is as good as his players," veteran reliever Bob Stanley said. "He was a good manager in '86. We won. We haven't played well since."

Gorman said Morgan, who spent 16 seasons as a minor-league manager and had been Boston's third-base coach this year, would have the job on a "day-to-day" basis. "We'll play it by ear," he said.

"I have in my mind the thought of some possible candidates who could be replacements," Gorman added. "Certainly we'll give Joe Morgan consideration. Certainly we'll give Ed Nottle, our Triple-A manager, equal consideration. But we'll look around and take the time to find the right guy to run the ball club."

He said the Red Sox also would consider candidates outside the organization. He said he had some in mind but refused to identify them.

Nottle manages Pawtucket of the International League, a job Morgan held from 1974 through 1982.

Morgan's debut was delayed a day when Thursday night's opener of a four-game series with the Kansas City Royals was postponed by rain after a delay of two hours, 39 minutes. It was rescheduled as part of a twinight doubleheader tonight.

"Joe Morgan is a great guy. He seems to be a motivator and hopefully he'll put some spark into this ballclub," said left fielder Mike Greenwell, the major leagues' RBI leader. "Hopefully, a change of atmosphere will turn the team around."

Asked how he would change things, Morgan said pitching normally would take care of itself.

"What we have to do is take advantage of the baserunners we've had, which I don't think we did during the first part of the season," he said.

Morgan, a light-hitting infielder who played sparingly in four major league seasons, joined Boston as first-base coach in 1985. He said he had not been guaranteed the managerial job beyond this season but added, "the word interim never entered my vocabulary."

The idea of ever becoming a major league manager hadn't entered his thoughts much recently.

"I never wanted to take over another man's job in midstream, but the chance is here now, a chance I had figured had gone by the boards," he said. "I figure that at my age and after 12 years in Triple-A that I probably would never manage in the big leagues."

Now Red Sox owner Jean Yawkey, hoping to get the team back in the pennant race, has given him his chance.

Gorman said the club's owners began meeting at 2:30 p.m. Thursday and called him in an hour later to tell him Mrs. Yawkey had decided to change managers.

Morgan said he had no indication a change was imminent until Gorman told him he had the job.

The move also came as a surprise to McNamara. His job had been in jeopardy for much of the season, but he figured he had weathered the latest crisis by not being fired during the three-day All-Star break that ended Wednesday.

"I'm happy I survived another deadline," McNamara said Thursday, soon after arriving at Fenway Park. Not long after, he learned otherwise and quickly left the stadium.

Haywood Sullivan, a part owner of the team, said he opposed the move.

But, he admitted, "It's easier to change leadership than change the entire 24-man roster."

According to a team statement, Mrs. Yawkey felt "a change in leadership was necessary if the Red Sox are to make a serious attempt at winning the Eastern Division title."

McNamara is the sixth manager to be fired this season, following Cal Ripken of Baltimore and Billy Martin of the New York Yankees, Larry Bowa of San Diego, Chuck Tanner of Atlanta and Dick Williams of Seattle.

McNamara had managed Oakland, San Diego, Cincinnati and California before succeeding Ralph Houk in Boston on Oct. 18, 1984. With the Red Sox, McNamara compiled a 297-273 record.

This year's mark was the one that cost him his job.

With a wealth of young talent led by Greenwell and Ellis Burks and the off-season acquisition of reliever Lee Smith, the Red Sox were a popular preseason choice to win the division.

Although they led the majors with a .287 batting average at the All-Star break, the Red Sox suffered from inconsistent pitching.

"They don't fire 24 guys and bring in 24 new guys," said third baseman Wade Boggs, the object of a palimony suit that added to the team's concerns. "We were playing inconsistent baseball. It wasn't like John was striking out or giving up home runs. The players are to blame."