An unhinged spa worker slashed her 43-year-old colleague during a wild fight Sunday inside a Manhattan massage parlor, police said. 

The women were arguing when the dust-up turned violent, leading the enraged employee to slice up her rival in the King Spa on East 57 Street and Second Avenue around 3:20 p.m. according to officials. 

Stock photo of police tapeA massage parlor worker stabbed her rival during a fight in a Manhattan spa, cops said. Christopher Sadowski

Medics rushed the wounded victim to NewYork-Presbyterian/Weill Cornell Medical Center where she was listed in stable condition. 

The attacker, described by police as in her 50s, fled the Midtown East business in a black BMW and has yet to be caught. 

Last year, a customer touted King Spa’s “professionalism” in an online review of its services. 

“Professionalism at its finest! The therapist’s expertise shone through, and the massage left me invigorated. A definite repeat,” the enthused client said. 

The Post was unable to reach the spa Monday afternoon.