Juan Pablo Montoya was left fuming at Iowa after late race contact left him hitting the wall with just under 20 laps remaining in the Iowa Corn Indy 300 on Saturday night.

Montoya had been running in seventh place when he took the low line to pass Ed Carpenter on lap 281, but Carpenter was himself also sweeping down the track and forcing Montoya lower and lower, until the Penske #2 spun out and went into the wall ending the Colombia's day.

"I got inside of him and he was running high and then all of a sudden decided to run low," said a less than happy Montoya. "He had been running every lap on the top. I got a run I got inside of him and he just turned down on me. Very frustrating deal but we have to move on."

Montoya stayed standing on the track next to his wrecked car long enough to indicate his displeasure to Carpenter as the field came back round behind the safety car, before being led away by the safety officials.

Afterwards, Carpenter admitted that it had been his fault but insisted that it hadn't been a deliberate block.

"I feel bad, I certainly wasn't trying to take him out," he insisted. "Our Fuzzy's car had understeer all race and we were just hanging on at the end of the race ... I'm sorry that he crashed but I didn't do it on purpose. I was hanging on with my tyres and I didn't know that he was there.

"I knew he was working the inside. I was struggling, I was just going to try the low side that time. I didn't know he was that far in there. Lee - my spotter - told me he was there but it was too late, I'd already started coming down.

"My apologies, I definitely wouldn't have appreciated that if I'd been at the other end of it but at the time time it wasn't intentional," he added after finishing the race in fifth position. "I have a lot of respect for Juan so hopefully we can talk about it without me getting my butt kicked!"

The caution for the Montoya/Carpenter incident was the last of the evening. The first had been for rain which ended up turning into 26-minute red flag, and the next was for Mikhail Aleshin spinning out at the restart on lap 48 and collecting AJ Foyt on the way.

"I just made a mistake, I spun," admitted Russian who was left nursing a bruised left wrist after the crash. "I didn't really know if I went below the line on the exit, but in any case, suddenly the rear of the car just went and there was nothing I could do about it at this point. So I feel very sorry for my team because obviously we had a nice car in the front. We were in a good place today."

"I just couldn't see anything," said Sato of the view of the incident from the cockpit of the #14 AJ Foyt Racing car. "It was all smoke and until I hit him, I couldn't see anything. I tried to avoid it ... Not a lot of damage, just bad luck."

The only other caution triggered by an accident was on lap 160 when Sebastian Saavedra ended up brushing the wall in turn 2 while running in an impressive third place. The KVSH Racing team got the car repaired but he was seven laps down, and eventually the car developed further issues that forced him to retire 42 laps form the finish.

"Very hard to describe how disappointed I am," said Saavedra. "This was our day, we had a car that I connected very well with. We were very loose from the beginning but I loved it and I was driving where I needed to drive it. Unfortunately at the end of the third stint, everyone was struggling with grip and my rear tyres were extremely worn and I just couldn't save this 'moment' and it ended our day."

Saavedra's team mate Sebastien Bourdais was already retired from the pit race, having been forced out of the running on lap 130.

"We're having electrical issues, the car keeps shutting off and resetting the ECU and every time it does that, it shuts off the engine," he reported. "First time it did it under yellow , it took a long time for the car to fire back up. I got it going again and then I thought it was fine then on bumps it would shut off every now and again. The engine kept running then finally on the back straight, it shut off completely and took a long time to restart.

"We just can't take the chance to run like that," he pointed out. "If it happens when I'm fighting for a position, I'm going to put someone in the fence. There's no point."

Also retiring from the race was Marco Andretti, who suffered another engine failure similar to that which cut his day short at Texas Motor Speedway last month.

"It was just a survival-type race," he said. "We were just trying to hang in to salvage something ... I'm just really bummed because I feel like we would have probably been on a similar strategy to [race winner and team mate] Ryan [Hunter-Reay] at the end.

Hunter-Reay won the race with a late pit stop to change to a fresh set of tyres, which Andretti said would have been his call if he'd still been running at that point of the race: "I always would have taken tyres. If I didn't have a shot at winning, I would have tried something that would have given me a shot, so definitely disappointed."

Dale Coyne Racing's Carlos Huertas also retired from the race, pulling into pit lane on lap 78 having already gone off the lead lap. Driver illness was cited, with a number of drivers at this weekend's event also apparently suffering from some malady including Penske's Will Power who had earlier been reported as having a suspected bronchial issue.

The Australian nonetheless completed the race, although a late handling issue saw him drop to 14th place at the line.