A feisty septuagenarian was clobbered by a man several decades his junior in Brooklyn, surveillance video released by police shows.

The 78-year-old victim was attacked when he got into an argument with a man in his 20s while in the lobby of a building near the corner of 50th St. and 8th Ave. in Sunset Park around 5 a.m. Apr. 30, police said.

The video, released Monday, shows the assailant punching the man several times in the head before throwing him against a wall and knocking him to the ground.

The victim suffered cuts and bruises to his face and head. He was treated at Maimonides Medical Center.