The punch was thrown during a heated post-race confrontation following the Richmond Sprint Cup race, in which Ambrose and Mears took the flag in 18th and 19th respectively.
CLICK HERE for Speedcafe.com's earlier story including footage of the incident
Murphy and Ambrose almost came to blows shortly before the Ford driver's switch from V8 Supercars to NASCAR at the end of 2005.
Murphy watched video of today's incident in between V8 SuperTourer driving duties and local television commitments at Pukekohe's ITM 500 Auckland.
“I didn't think he had it in him, but there you go, I'm wrong again,” an amused Murphy told Speedcafe.com.
“I've got to pay credit to that one. It looked like it was a pretty good hook!
“Maybe he wasn't going to let it slide two times in a row.
“Maybe he saw a picture of my head on Casey Mears' shoulders, who knows?
“He obviously got a big shove from Casey for whatever reason that moved him aside and that was enough to get him riled up.
“It was very entertaining!”
The pair had laughed about the incident during Speed Channel's coverage of the 2011 Bathurst 1000, where the American channel surprised Ambrose by adding Murphy to a live phone interview.