Soldier, 18, victim of stab attack
The 18-year-old is recovering in hospital after the assault in Port Glasgow in the early hours of Sunday.
Police are treating the incident in the Clune Brae area as attempted murder.
The serviceman called for help after fleeing down Brookfield Road and on to High Carnegie Road, Strathclyde Police said.
Doctors at Inverclyde Royal Hospital in Greenock described his condition as serious but stable.
Detective Constable Gary Gillen said: "Extensive police inquiries are ongoing to establish the circumstances surrounding this violent attack and exactly where it took place.
"Officers are currently carrying out door-to-door inquiries and checking CCTV footage in the local area to try and gather more information.
"I would ask anyone with any information that may help police inquiries to come forward as a matter of urgency."
The suspect is thought to be in his 20s, around 5ft 2in tall and of stocky build.
Police did not disclose which regiment the soldier is serving with.