Paul Casey is not allowing his American coach to take any of the blame for him crashing off the leaderboard at the Open championship.

Peter Kostis had to return to the States after watching the 26-year-old set the pace at Royal Troon with an opening 66 on Thursday.

Casey's second-round 77 dropped him eight strokes behind and after producing a one-under 70 today to stand level par he stated: "Peter rang me last night and said he felt bad. He felt like he let me down and that there were a couple of things he should have said.

"It was unfortunate he couldn't stay, but it's not his fault. I'm working on stuff and it was evident I've not got it done yet.

"There's nothing I can do about it now. This is the first time I've played the weekend of an Open and I'll definitely learn something, so that's what I'm concentrating on.

"Everybody is going to work on stuff during big events because the off-season is so short that there's just not enough time.

"The one thing I've been struggling to do is cut the ball and once again today I had a rough start.

I've no problem on the way home, but it's annoying because there are opportunities on the way out and I haven't been able to take them."

Casey's 70 started and finished with a bogey, but there was also a hat-trick of birdies from the fourth and after a dropped shot at the ninth he rolled in an 18-foot birdie putt on the 490-yard par-four 11th.

Asked if there was a point following his 77 that he just went "darn it" - or words to that effect - he said: "All evening."

The damage it did was brought home to him as he spoke.

Halfway leaders Skip Kendall and Thomas Levet walked past him to the first tee to begin their third rounds.