'Rodgers has bared his teeth'

He's not had to do it before now in a season of successes so far, but you sense the Celtic manager feels it's time some of his players got a little kick up the backside.

When Brendan Rodgers says his side failed to the do the "basics" at Dens Park and were too "soft", there's method to the criticism.

After an incredibly consistent series of away performances in the Premiership during which not a single point was dropped until just before Christmas, things have done distinctly off the boil.

It's hardly crisis time, but by Celtic's very high standards this season, there's been a bit of a drop-off in level.

Just the one win in their last four league games away from home; two draws in Dundee and, of course, the humbling at the home of Rangers.

That was the last match Liam Scales started. I wonder if the Republic of Ireland centre-back is about to regain his place in the starting 11.

He's been one of the stand-out performers since Rodgers returned to Glasgow's East End, prompting the manager memorably to say few players have surprised and impressed him more in his whole managerial career.

Celtic splashed out around £6m for Auston Trusty, so it's only natural they'd try to get him in the side. No-one is going to oust Cameron Carter-Vickers from the team, rightly so given his steadying influence.

So it was Scales who had to make way for the other towering American. Trusty has failed fully to convince, however, and it was he who bore the brunt of his boss' ire for the concession of the Dundee's third goal.

He was also substituted at half-time in the League Cup final, so poor were Celtic with the ball in that first 45. Scales came on and the side's distribution was instantly better and quicker.

If Celtic (and by direct implication, Trusty) were too soft on Tayside, they'll need to harden up quickly for the visit of Kilmarnock in the Scottish Cup this weekend.

Derek McInnes' side is physical and very well-organised. Slip-ups at home have been few and far between on the domestic front for Celtic, but you only get one shot in the cup, so normal service will have to be resumed sharp-ish if Rodgers wants to preserve the chance to go for (yet) another treble.

It's hard for any athlete to maintain full intensity when their race is all but run.

Celtic's lead at the top of the table - whether 16, 15 or 13 points once the midweek business is done - means they know they're pretty much uncatchable.

They're two-thirds of the way towards their ultimate domestic dream. There's no margin for error in the knock-out competitions, though, so if the basics are not being done by certain players, there are others on the bench to whom the manager is likely to turn.

Trusty is not alone in having to worry about his starting place. Adam Idah, while still contributing to the team, needs a goal or two and quickly.

Reo Hatate can either dazzle or disappear. Seemingly in equal measure. Captain Callum McGregor is asked to shoulder a lot of responsibility: too much, at times? Could others share the load better?

Celtic spent about £26m on Arnie Engels, Idah and Trusty in the last transfer window. While that may at one point turn into good value for money, that point is far from being reached.

The manager is likely to recruit one or two more new additions soon, given he'll have to navigate Champions League qualifying in the summer. It's hugely beneficial to bed players in rather than sign them in July and hope they're OK to pitch straight in.

If he's having to tell a few home truths to some of his squad at the moment, there'll be an even more ominous message for some of them round the corner if the desired reinforcements do indeed arrive in the next week or two.