Aston Villa midfielder Stiliyan Petrov admits he cringes over his time at Celtic under former manager John Barnes.

"I played at right-back and I was awful," Petrov told the Sunday Mercury.

"It was a poor start to my Celtic career playing at right-back. It was awful. Very bad. It wasn't very pleasant.

"I think because I was a new signing they wanted to play me but other midfielders like Eyal Berkovic and Lubomir Moravcik were doing well.

"John Barnes saw something in me that made him think I could do well at right-back. He was wrong.

"I was probably the slowest right-back in the Scottish Premier League! So it didn't work for me and I'm glad that I moved away from that position."