RONNY DEILA has talked the talk.

It is now time for the Celtic manager and his players to walk the walk.

The Norwegian, it must be said, has made quite an impression since taking over from Neil Lennon in the summer and sharing with his predecessor a most astute understanding of what it takes to create a headline.

We've had chips being banned from the training ground, winning at Pittodrie bringing on an orgasm, ambitions of capturing a domestic treble along with the Europa League voiced with confidence and a controversial and continuing defence of Aleksandar Tonev following his suspension for allegedly using racist language.

It is on the park, unfortunately, where Deila has failed to leave his mark. His quip about beating Aberdeen being better than sex is starting to take on new meaning against the backdrop of increasing doubts over the stamina Celtic possess for a long and gruelling campaign.

On paper, they should have the SPFL Championship wrapped up by now. They have decent strength in depth, the biggest wage bill in the country and far greater punch in the transfer market than anyone else in the division.

Yet, 18 games into a 38-game season, they find themselves just two points clear of Aberdeen. As Jaroslaw Fojut stated at the weekend, Dundee United see themselves as contenders, too, despite slipping up at St Johnstone and failing to join the Dons in joint-second spot.

Joe Miller maintains a close connection with Celtic through his work with the club's Former Players' Association. He also enjoyed two spells at Aberdeen during the course of his career, though, and squeezed in a season at Tannadice as well.

Ask him how the title race stands right now and he is clear. Everything is up for grabs and will remain so until the end of the season unless Celtic can use the month of January to show the killer instinct that has been so badly lacking to date.

"I think the title race is wide open," said Miller. "No team is playing with real consistency and showing signs of running away with the league, so there is an awful lot to play for.

"January is going to be hugely important for everyone. If Celtic are looking to stretch their lead and look like title-winners, they have to begin now.

"I watched most of Celtic's games at the start of the season and have been waiting for them to hit the consistency level that you would expect, but it hasn't happened. I now don't know if it will.

"Aberdeen and Dundee United have put up a great challenge and Derek McInnes has done a terrific job at Pittodrie, but I put Celtic's position down to a number of factors.

"They haven't replaced the players who left and Deila has taken a while to settle. He has utilised most of the squad, some players are getting older and there just isn't the same quality there as there used to be.

"The fans are getting frustrated and edgy now as well. Without Rangers, Celtic should be picking up doubles and trebles and it hasn't been happening.

"I am still confident Celtic will win it in the end, but it is at a stage now where they are leaving the door open. They need to give themselves a boot up the backside if they want the title."

If that doesn't happen, Deila will surely be toast. Miller admits that, unless results improve dramatically, it can only be a matter of time until the pressure intensifies upon him.

"It is his first season, but you have got to hit the ground running at Celtic," he said. "It is a massive club. The fans demand that.

"You cannot have a season where you are not winning titles, especially when there is no Rangers. Champions League football is at stake here."

For Aberdeen, a fifth consecutive league victory over Inverness Caledonian Thistle at the weekend put them within touching distance of the defending champions. Eight clean sheets in their past 10 matches have heightened hopes that they may, indeed, be strong enough to make a sustained challenge.

Willie Miller, a bona-fide club legend in addition to being a former captain and manager, is not prone to outlandish statements. He clearly believes, however, that we could be on the brink of seeing a new light in the north.

"If they can keep this run going and steer clear of injuries, they are going to be title challengers," he said. "We're almost at the halfway stage and there are only two points in it.

"I don't see Celtic dominating the second half of the season because they haven't shown that they are capable of doing that.

"Aberdeen should be looking at it as a possibility.

"I wouldn't take Inverness Caley Thistle out of the mix. They were unfortunate not to get something out of the game and Dundee United will be bitterly disappointed to have lost on Saturday."

Aberdeen's current manager, McInnes, of course, has been playing down any talk of winning a first championship since 1985. Joe Miller, who won a League Cup and a Scottish Cup at Pittodrie, appreciates the psychology of managing expectation, but suspects the true feeling within the squad will be somewhat different.

"I am sure the experience they had in winning the League Cup last season should give them every incentive to go for the league," he said.

"The question is whether they can develop consistency and a run of form as well. Derek has been good in terms of trying to play things down and stop people from getting too excited.

"The place will be jumping if Aberdeen can stay in contention, though. It is something people have not seen for over 20 years up there.

"If Aberdeen were to win the title, Derek would get the keys to the city."