Former boxer Mike Watson was injured after a suspected rush-hour car-jacking attempt, a spokesman for the ex-sportsman said.
The 51-year-old, who was partially disabled after suffering a near-fatal brain injury during a WBO super-middleweight title clash with Chris Eubank in 1991, spent time in hospital after the attack on the Ridgeway in Chingford, east London, on Thursday.
Friend Lennard Ballack, who was in the car with Mr Watson at the time, was also hospitalised after one of the suspects sprayed a substance in his eyes.
Mr Watson is also believed to have been sprayed.
The victims are now recovering at home following the incident.
A spokesman for Mr Watson told the Press Association: "Somebody bumped into the back of the car that Michael and Lennard were in.
"There didn't appear to be any damage, but Lennard got out to speak to the people in the car behind them.
"From what I understand, the guys wound down their window and sprayed something in his eyes.
"The men then went to the car that Michael was in - he had his seatbelt half off by this point, and they dragged him out the car and along the floor. We are assuming it was an attempted car-jacking.
"The men then sprayed Lennard in the eyes again and drove away."
The suspects left the scene in a different vehicle, while the former world title challenger and his friend were left prone on the floor.
The spokesman said: "Lennard's suffering a bit - his eyes are not good. Michael is okay.
"I think he is very, very sore though. He got dragged along the road so some of the skin has broken badly.
"I gather the police have been very good, so the aim now is to catch the people who did this."
A Metropolitan Police spokesman confirmed officers were called to the scene shortly before 5pm to reports of an attempted robbery.
He said: "Two men, aged in their 50s, informed officers that they had been sprayed in the face with a suspected noxious substance by two suspects who attempted to steal the car.
"The male suspects fled the scene in a different vehicle.
"The victims were assessed at the scene by the London Ambulance Service before being taken to an east London hospital for further treatment - their injuries are not life-threatening."
Anyone with information about the incident is asked to contact police.