Celtic new boy Paul Hartley is looking forward to the challenge ahead with the Bhoys, having sealed his switch from Hearts for an undisclosed fee.
The 30-year-old Scotland midfielder has signed a two-and-a-half year deal with the SPL leaders, following Steven Pressley in making the move from Tynecastle.
He told his new club's official website: "I had a fantastic three-and-a-half years at Hearts and I don't want to say anything about the club. I leave a lot of good friends there.
"I had a great time and now it's a new challenge for me coming here. I'm a Celtic player now and I just want to concentrate on doing well here.
"I've spoken to Steven in the last couple of weeks and he's said it's such a joy to be here.
"It's a terrific dressing-room, they've got a winning mentality and I want to be part of it."