A black man tried to help a white, boozed up guy who had stumbled into his table at a West Village restaurant— but wound up knocking him out when shouted the N-word, cops said.

Douglas Reddish, 25, ate with his girlfriend at Benny’s Burritos on Greenwich Ave. on Friday night when the soused stranger knocked into their outdoor table, authorities said.

Reddish steadied him since he lost his footing, cops said. Waiters had been rushing over to shoo him away.

“This n—-r wants to fight me,” the belligerent man roared, cops said.

Then Reddish punched him, cops said.

He fell backwards and landed on the sidewalk. His head smashed against the concrete curb and bled profusely, cops said.

“He was out cold. I thought he was dead,” said Benny’s worker Robert Garcia.

Not realizing how much damage he inflicted, Reddish went in for another blow, but was held back by employees, cops said.

When Reddish saw the blood oozing he fled the scene, leaving his girlfriend at the burrito joint, police said.

He didn’t get far.

Police arrested him blocks away and charged him with assault for attacking the unidentified man, who is believed to be in his 30s.

A woman who spoke with the drunken man on the street before he was knocked out said he was upset over his wife leaving him and about his “job at Goldman Sachs.”

“I felt so bad,” she said. “He could hardly walk.”

A Goldman Sachs spokeswoman said they have no clue who the belligerent man is, and that he doesn’t appear to be an employee. “We have no record of him,” the spokeswoman said. .

The angry white man was taken to Beth Israel Hospital, authorities said.