A motorist said his nose was broken and he suffered bite marks in what he describes as a horrific road rage attack.
The Bolton man, who wishes not to be named, told The Bolton News he was driving along the M61 towards Bolton in his work van on August 1 at just after noon.
Inadvertently he pulled out into the fast lane in front of a fellow motorist.
Lancashire Police confirmed they are investigating an assault.
The 27-year-old said: "I was working, driving from the Chorley area towards Bolton. I pulled into the third lane of the motorway and that is when I noticed the guy behind me, swerving behind me and flashing his lights.
"I pulled out by mistake. I carried on driving in the third lane, but the next minute he was in the middle lane next to me pointing to the hard shoulder.
"I continued driving as normal, but then he shot in front of me and braked suddenly, putting mine and other people's lives in danger.
"He continued driving erratically, so I pulled over to the first lane and slowed down from 70mph to 50-55mph, then he followed me, still swerving and flashing his lights and trying to make me pull over."
The motorist said the driver pulled onto the hard shoulder alongside him.
The victim decided to pull into Rivington services, beckoning the motorist over.
He said: "I pulled in and, thank the Lord, another motorist who had seen it all also followed us into the services.
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"I wound my window down, he (the attacker) didn't say anything, he just smacked me straight in the face.
"He gave me a couple of punches to the face through the window as I was sat in my van, I still had my seatbelt on.
"I put my head onto the passenger seat to get my face away, then he smacked me on the back of the head."
He added: "I used my hand to try and push him away, but then he bit my arm and was growling, saying 'I'm going to f******g kill you'.
"The witness then pulled him out and I went into the services to clean myself."
The motorist claims the attacker then fled the scene.
After this, the victim reported the attack to the police and was given first aid - he was advised to go to hospital, however.
An X-ray found he had a broken nose and he was given a hepatitis shot - he will have to return for a further shot.
He continued: "I have been driving for nine years and I have never been in that situation.
"It was totally frightening, it is still sending shivers down my spine just thinking about it. I feared for my life.
"I have got teeth marks on my arm, it has scabbed, I'm going to have this for the rest of my life, it's horrible.
"I am an electrician by trade, my right arm is the one I use for work when screwing and drilling, and when I'm doing that work I'm in pain."
Lancashire Police said enquiries are ongoing.
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