Australia's Will Power was in apologetic mood after his second run-in with Kiwi driver Scott Dixon in as many weeks at the Indycar Grand Prix of Baltimore.
Power's car swerved right in front of Dixon during a restart and both hit the wall, ruining their hopes in a crash-marred race where almost every car in the 24-strong field sustained some kind of damage.
Power made it to the pit, but he was given a penalty for interference and finished 18th, one spot ahead of Dixon who was unable to continue.
The Baltimore incident came a week after Power's first win of the year at Sonoma, California, was soured when Dixon accused one of the Queenslander's pit crew of gamesmanship.
The New Zealander lost the lead late in the race after sustaining a drive-through penalty for clipping a tyre held by the crew man and sending him sprawling as he exited pitlane.