Police were looking for the man suspected of stabbing a straphanger in the chest at Manhattan’s busiest subway station Saturday evening.

The attack unfolded just after 8 p.m. in the Times Square station at W 40th Street and Seventh Avenue, according to the NYPD.

A 51-year-old man was stabbed in the chest and taken to Bellevue Hospital for treatment, cops said.

The altercation was unprovoked, and the knife-wielding man was believed to be “possibly homeless,” law enforcement sources told The Post.

The suspect remained at large Sunday morning.