"I wasn't happy with my performance," said the Scottish defender, on loan from Newcastle. "I'm sure I can do better and I want to prove to the fans I can.
"Derby are a big club and as soon as George Burley phoned Newcastle at 4 o'clock on Friday afternoon I told him I wanted to come down here.
"There are a lot of young players here but Manchester United have proved you can win things with young players if they're good enough.
"But it's a tough league in the First Division, I found that out last season when I was on loan with Coventry."