A man fatally stabbed his 74-year-old uncle in the chest during a heated clash in Upper Manhattan early Friday, police sources said. 

The elderly victim was found unconscious and unresponsive inside an apartment building on West 151st Street near Broadway in Sugar Hill around 6 a.m., cops said. 

Investigators determined that his nephew had stabbed him once in the chest during a verbal dispute, sources said. It wasn’t immediately clear what the argument was about. 

The victim – who had not been identified by the late afternoon pending family notification – was pronounced dead at the scene, cops said. 

His nephew was taken into custody with charges pending, the sources said. 

At least one knife was recovered at the scene, according to sources.