The Scottish champions came out on top in the first clash of the season between the Glasgow rivals in a pulsating encounter yesterday.

The victory allowed Rangers to move four points clear of Celtic at the summit of the Clydesdale Bank Premier League but Naismith says the win must act as the springboard for forthcoming games.

He said: "For everybody at the club, it's a big game because it's the first Old Firm game of the season. It's probably been our best performance of the season.

"We have played good football at times in the games but in this game I thought we played good football throughout the 90 minutes and scored some good goals.

"Now we need to push on and take this performance into other games because, at the end of the day, it's just three points."

Holders Rangers face Falkirk in the Scottish Communities League Cup on Wednesday, before taking on Dunfermline in the SPL.

Naismith added: "There is no point in winning this game and then dropping points in the coming weeks so our main focus now is on Falkirk during the week and back into league action next weekend."

Naismith had so far failed to find the back of the net in an Old Firm derby but set the ball rolling with a superb strike that was cancelled out by Gary Hooper, before Badr El Kaddouri fired the Hoops into the lead at half-time.

Rangers hit back in the second half through goals from Nikica Jelavic and Kyle Lafferty, with Charlie Mulgrew seeing red for Celtic, before Naismith netted in injury time.

On finally scoring against Celtic, he said: "It just makes it that bit more special because it's probably the biggest fixture of the season.

"I've scored against most other teams but they had eluded me until now while I was at Rangers. Thankfully, I got a couple."

Goalkeeper Allan McGregor made an uncharacteristic error when he allowed El Kaddouri's strike to slip between his legs.

But boss Ally McCoist felt the blunder galvanised the rest of the team, a view which was echoed by Naismith.

He said: "It probably did play on the boys' minds in the second half because usually it's him saving us every week.

"It's a nice change for us to say that we saved him. But he's a quality goalie and I'm sure he won't let it bother him too much."