Rangers have been over the course and know what it takes to win but Celtic’s transfer activity means they will be a tough nut to crack in the title race, according to Brian Laudrup. 

The Great Dane has been impressed by the quality and scale of Celtic’s transfer work, bringing in three Japanese players - Daizen Maeda, Reo Hatate and Yosuke Ideguchi. 

More look set to arrive with Aussie international Riley McGree also considered a done deal. 

And Laudrup feels the stability in Giovanni van Bronckhorst’s ranks will be cruical to stave off the threat from Parkhead. 

He told the Daily Mail: "While my old side are six points ahead at the top of the Premiership, I expect a real title challenge from Celtic when the league resumes next week. 

"Celtic won the first trophy of the season, beating Hibs in the League Cup final, and they went into the winter break in a good fashion. And I think it's fair to say from their January dealings that the Parkhead club are doing everything in their power to try to get back on top. 

"They are really on fire in terms of new signings. They have already secured the signatures of three players from Japan's J-League in Daizen Maeda, Reo Hatate and Yosuke Ideguchi. 

"Perhaps a few people won't know these players but if you look at the stats around them, Hatate was in the Team of the Season in Japan and Maeda was joint-top goalscorer in the league. 

"It is always a delicate moment when you join a club halfway through the season, though. And when you buy a number of players in January, it's always going to take some time. 

"You don't have a pre-season. You don't have friendly matches. You have to do the business right away. It's going to be very interesting to see what impact these players have. 

"It would be harsh to expect them to hit the ground running like Kyogo Furuhashi has done. He's been a smash hit since moving to Scotland. 

"But what's clear is that Celtic are certainly showing their intent in January. They are going for it, that's for sure. That has to keep Rangers on their toes. 

"They have already brought in the versatile James Sands on loan from New York City but it's going to be very interesting to see how much money Rangers are going to spend this month after selling Nathan Patterson to Everton for a club-record £12million. 

"What Rangers do have in their favour is consistency and stability. That is very important for any manager. 

"While Celtic have new players coming into the club, the players are already there at Rangers. 

"They've been there together for a few years and they know the club and its demands. They've been through the success of winning the title last season. They know what it takes to win."