Gers ace Lee insists Hoops are favourites

While debt-ridden Rangers were unable to make a permanent signing for the third transfer window in succession, Celtic added eight players to their ranks including on-loan Barclays Premier League strikers Robbie Keane and Diomansy Kamara.

While no doubt trying to add to the pressure already being felt by Tony Mowbray's side, McCulloch said: "We're not silly enough to forget that with the next game everything can turn again, so we just need to keep doing what we're doing.

"I think Celtic have to be favourites to win the game with the players they have brought in.

"With the rest of the signings I think they have around six strikers, and some good players, but we will not be rolling over. We'll be up for the challenge, that's for sure."

McCulloch is one of a number of success stories for Walter Smith's men over the past few months.

The 31-year-old was recalled to Craig Levein's first Scotland squad for next week's friendly against the Czech Republic after withdrawing his services to previous boss George Burley.

With both Maurice Edu and the now departed Pedro Mendes having missed long spells of the season through injury, McCulloch has held down a regular place in the Rangers central midfield and the versatile player feels he has benefited from the stability.

"I don't know about the best football of my career, but it's definitely the best of my Rangers career," the former Motherwell and Wigan player said.

"I've got players alongside me on form, too, and that's what makes it easier. We're in a good team and the boys around me are playing well.

"I'm just trying to enjoy it. If we can come out this season being as successful as the boys want to be, then it will be one hell of a summer. We've got a dressing room full of guys who hate to lose at anything and that kind of mentality rubs off on everyone."