Bobby Murcer beat the Baltimore Orioles tonight. He did it while mentally and physically exhausted and he said he did it entirely for his late friend, Thurman Munson.

First, Murcer cracked a three-run homer off Dennis Martinez to bring the New York Yankees back to 4-3 from a 4-0 deficit in the seventh inning.

Then, in the bottom of the ninth with one run still to go, he smashed reliever Tippy Martinez's offering down the left field line and watched Bucky Dent and Willie Randolph scamper home for the 5-4 victory.

Murcer said he didn't sleep Sunday night. He was keyed up, preparing to address Munson's relatives, friends and teammates at the catcher's funeral in Canton, Ohio today.

The other Yankees were shipped from the long day in Canton, as well, but Murcer said there was tremendous excitement on the bench. "We felt all along we were going to win this game. I think it was understood we were going to win it for Thurman."

When he came to bat in the ninth, said the red-eyed outfielder, "I just didn't feel like he was going to get me out."

The loss left the Orioles with a split of the Yankee series. All four games were decided by one run.

The Orioles emerged with seven wins in this crucial 10-game road trip and a six-game lead over the second place Boston Red Sox. They will head back to Baltimore Tuesday for the longest home stand of the year, opening at 7:30 p.m. with the Milwaukee Brewers.

Murcer had help tonight. The Orioles gave it to him.

Tippy Martinez had worked the Birds out of a jam after Murcer homered off starter Dennis Martinez in the seventh. It was his first home run since returning to the Yankees in June.But in the ninth reliever Martinez made his own jam.

He walked Dent leading off. Then, when Randolph set down a sacrifice bunt, the ace reliever raced from the mound, scooped it up and heaved it wildly past first baseman Eddie Murray into right field.

Randolph and Dent raced to second and third and awaited Murcer.

The veteran center fielder delivered.

Before Murcer's homer it looked as if the game was in hand for the streaking Orioles. Lee May pounced his 16th homer of the year, off Yankee hurler Ron Guidry in the second. The designated hitter, rebounding from four straight strikeouts in Sunday's game, doubled in the fifth and scored on Rich Dauer's sacrifice fly for a 2-0 Baltimore lead.

Then strong man Ken Singleton whacked his 28th homer, over the right field wall near the 385-foot marker for two more runs in the sixth inning.

Oriole starter Martinez looked comfortable with a 4-0 lead.

But Murcer had other ideas.

In the seventh Martinez retired the first two batters but walked Dent. . Randolph whacked a double down the left field line to put men at second and third.

It was the same scene Murcer was to face in the ninth, but he faced a different Martinez. This time he picked on a picture-perfect high fast ball our over the plate. He creamed it 10 rows back into the seats near the right field foul pole.

Tippy Martinez relieved after Dennis gave up a single to the next man, Chris Chambliss, and he held the Yanks through the eighth.

For Murcer the game was doubly satisfying because it broke the slump he's labored in all year.

He was batting .220 at game time, with no homers and five runs batted in. He doubled the RBI total tonight.

In whispered tones in the locker room he described how it felt: "Thurman and I were both struggling this year.

"On Wednesday night (the night before Munson died in his jet) I took him to the airport.

I told him, "If I get my stuff together, will you get yours?"

"He told me, "Youd better believe it.""

And on the day the governor or New York declared a state-wide day of mourning for the Yankee captain, his best friend on the team got his stuff together.

The Yankees seemed to awaken from their day-long ordeal as the game wore on. Manager Billy Martin typified the club's mood before game time.

"I wish somebody would come up and punch me in the nose," he muttered.

Somebody asked why.

"So I could turn around and hit him about 500 times, and get this hurtin" out of me."

The Orioles gathered before the game for a brief, private pep talk from owner Jerold Hoffberger, who will turn over the reins on Nov. 7 to Washington lawyer Edward Bennett Williams.

Hoffberger said the talk had nothing to do with the recent sale of the team or with questions about whether some games will be played in Washington next year.

Hoffberger said he has not decided whether he will accept Williams' offer to stay on as president of the club next year.

Outfielder Gary Roenicke sat out again tonight with a slow-healing sore back. Jim Palmer, whose mandatory 21 day stint on the disabled list could have ended today, stayed on the disabled list. He threw on the sidelines before the game, seemed strong, and is expected back in the rotation in a matter of days.