Daniel Ricciardo felt "pretty small" after he reversed into Daniil Kvyat in a bizarre incident that forced both drivers to retire from the Azerbaijan Grand Prix and landed the Australian a three-place grid penalty.
Renault driver Ricciardo attempted to overtake his former Red Bull team-mate – running 10th at the time – at turn three in Baku but overran and ended up going down the escape route.
The Toro Rosso followed him and, in his haste to get back on track, Ricciardo reversed straight into Kvyat and the damage sustained brought their respective races to a premature end.
The incident was investigated after the grand prix and the stewards issued Ricciardo, who apologised to Kvyat in the media area, with a gird penalty for the Spanish Grand Prix.
"I obviously don't feel good about it. At the time it was looking quite good for us, starting to pick up the pace and close in on Dany. I saw a gap and thought I'd have a go," Ricciardo told reporters.
"It's always tight into three but initially I thought I was going to pull it off, then I felt I was going to start to lock and then miss the corner.
"Then as soon as I went down the escape road I guess it was just a sense of urgency and a bit of panic, just trying to minimise damage and lose as little time as possible, so I found reverse and started going. To be honest I had no idea he was there.
"I guess the urgency stopped me from looking and when I went long I just thought he would've cut back and stayed on track.
"I was just trying to minimise the mistake I made which turned into another mistake. Kinda c***** on my part, I certainly feel bad for the team and for Dany, but I felt the team deserved more than that. There were positives with the pace, but not the way I wanted to end it.
"All weekend we haven't really been on it, so getting into the points would've been a fairly good recovery for us. If we'd finished I think we would've been quite upbeat about it. I feel pretty small at the moment. It was just a silly mistake."
Kvyat held nothing against Ricciardo in the aftermath and took a philosophical stance on a disappointing end to what looked set to be a solid outing.
"These things happen, it's racing like I always say when I make a mistake. It happens, that's all I can say. I was a bit disappointed right in the moment, but what can I do about it," said Kvyat.
"There was potential for maybe a point or two today, which I would have definitely taken because the team deserved it a lot because yesterday, in qualifying, our car was great.
"Today we had a bit of a tyre management issue. We move onto the next one. We have a strong package. I'm sure our time will come."