Carpenter apologises for Montoya crash during Iowa IndyCar race

Montoya, who had recovered from going a lap down earlier when a piece fell off his rear wing, dived into Carpenter's inside with 19 laps remaining in an attempt to claim sixth, only for Carpenter to turn down onto the low line and cut across the front of the Colombian's car.

Montoya was spun up the track and into the outside barrier, and a track worker appeared to restrain him from attempting to approach Carpenter's car the next time it came passed under caution.

"I got inside of Ed and he was running high, and all of a sudden he decided to run low," said a furious Montoya.

"He'd been running high all night. I got a run, I got inside of him ... they all love preaching safe racing and everything, but when you go to pass them they're just douchebags."

The crash was reviewed by race control, who decided not to take action, but Montoya remained unswayed.

"I'll take action later," he said.

Carpenter, who used a similar strategy to race-winner Ryan Hunter-Reay in putting on new tyres for the final restart and finished fifth, admitted that he sympathised with Montoya, but was adamant that he had not intended to cause an accident.

"I feel bad," he said. "I certainly wasn't trying to take him out.

"I knew he had been working the inside; I was struggling and I was going to try the low side that time, and I didn't know he was there.

"My spotter was trying to tell me he was there but it was too late, I'd already started coming down.

"So my apologies, I definitely wouldn't have appreciated it if I was on the other end of it, but at the same time it wasn't intentional.

"I have a lot of respect for Juan, so hopefully we can talk about it without me getting my butt kicked."