Rangers find themselves trailing leaders Celtic by seven points after a home defeat in the Old Firm derby. Scott McDonald scored the only goal of the game for the visitors early in the second half.

Gers boss Walter Smith says his team must stay undefeated for the rest of the season to have any hope of claiming the SPL.

"It means there is no real margin for error for us now," he told Setanta Sports.

"We were obviously hoping to peg Celtic back. We didn't do so and we face a situation where we have to try to go the rest of the season undefeated if we are to pull them back."

Smith added: "It's the third game we have lost in the league and we have to improve dramatically on that before the end of the season.

"That's the challenge that's there for us.

"As with a lot of the Old Firm games recently, there wasn't a lot between the teams and sometimes one goal either way can turn the game and that's what happened in today's game."

The game could have ended differently had a Kirk Broadfoot goal in the first half been allowed to stand.

"From where I was sitting, there were a lot of bodies in there," he said.

"If the referee judges that he has been fouled then we have to go with that."