An injured police dog managed to pin down a suspect despite the man repeatedly slamming a car door on its head.
German Shepherd Alfa detained the "violent and reckless individual" after police spotted he was driving a stolen car with fake number plates, Scotland Yard said.
The 36-year-old had tried to speed off after seeing flashing blue lights, but soon became stuck on a roundabout after reversing into a dog unit vehicle.
He struggled with an officer to keep the car door closed, slamming it on Alfa’s head "multiple times", before being removed by the officer and held by the animal, according to the Met.
The car was spotted on Harrow Manorway, Bexley, south-east London, in the early hours of Thursday morning, the Met said.
Alfa was taken to the vet for a check-up and kept there for observation but it is hoped he will make a full recovery.
The suspect has been arrested on suspicion of cruelty to an animal, theft of a motor vehicle, failing to stop for police, dangerous driving, going equipped to commit theft, criminal damage to a police vehicle and driving while disqualified and without insurance.
He remains in custody at a south-east London police station.
Superintendent Emma Richards said: "This officer and canine companion stopped at nothing to apprehend this violent and reckless individual, who showed no concern for the welfare of the public, police, or police animals in his actions.
"Our officers work day and night to make the streets of London a safer place, and this is a prime example of the kind of situations they encounter, but tackle with bravery and professionalism.
"We will be supporting the officer and PD Alfa over the coming days to ensure they both make a full recovery."
A new law designed to give extra legal protection to police dogs and horses last month passed the committee stage in the Houses of Parliament.
The Bill was named Finn’s Law after the police dog which was stabbed in the chest and head by a suspected robber while protecting his handler during a pursuit in 2016.