COMMENT: Since taking charge, Thomas Tuchel and Chelsea have been on an upward trajectory. But now, for the first time, things are beginning to creak. It's no crisis - at least not yet - but Tuchel and his methods are now being tested... and at the most testing time of any competition anywhere in the world...

As we say, it's hardly the stuff of crisis, but Chelseais beginning to wobble... at least just a bit. Six goals conceded in the last two games. Two wins in five in the league - and the loss of the leadership. It is beginning to creak. And with a first ever Christmas programme to combat, Chelsea are entering the unknown with this manager.

After the collapse in St Petersburg, Cesar Azpilicueta recognised things had begun to go awry for the European champions. While calling for some perspective, the captain conceded for expectations at Chelsea, the past few weeks haven't been up to standard.

"It is true, as you said, that in Chelsea, you don't need a big number of defeats in a row to call it a bad period or a crisis," admitted Azpilicueta. "It is part of this club's ambition to go into every competition with the ambition to compete at the top. Last season, in December, we were top of the group and top of the Premier League and we had a very bad run of results."

That run last season ended with the sacking of Frank Lampard. And while his skipper has dismissed claims of history repeating, Tuchel is now facing his first big test as Chelsea manager.

For the moment, Tuchel has been celebrated. For his tactics. His approach. His honesty. The press and pundits have given him a pass on how he's managed his players in public. For this column, it's an approach that should be lauded. But there's little doubt for another manager. At another club. Such methods would be criticised. Attacked. And used to build a divide - at least publicly - between manager and dressing room.

Amongst a long line of 'em, the most brazen of admissions to come from Tuchel was his axing of Andreas Christensen. Not for form. Nor for fitness. But because of his umming and ahhing over signing the new contract put in front of him. Tuchel, with that public honesty of his, just laid it all out for us. The Dane was dumped to give him a hurry-up about penning his new deal, "We have the hope that it influences the contract situation a little bit," admitted Tuchel, flat out.

That's some negotiating tactic. Would another manager get away with it? Maybe not. But it's unlikely Tuchel will continue to avoid the scrutiny should results splutter as they do.

Chelsea's players appreciate Tuchel's matchday intensity

That's not to say there's any simmering revolt or even resentment amongst the players. Tuchel can count on their support. Wholeheartedly. Indeed, the senior members appreciate how the manager works. As intense as he is on matchday, Tuchel is the complete opposite through the week. The German and his staff a key influence on the spirit and unity that currently courses through the club.

But Tuchel is an outlier. Kai Havertz. Timo Werner. Certainly, Saul Niguez. They've all had their games pulled apart - publicly - by the German. For the moment, it's worked. At least in the case of the former two. And the results justify the approach. Indeed, if we get news of Christensen inking that new agreement in the coming days, Tuchel can feel well satisfied with himself.

But you do wonder if this is a dangerous game, particularly given current form. And it'll be fascinating to watch whether the manager reins himself in as he attempts to snap this stumble.

One player Tuchel will lean on to emerge from this slump is Romelu Lukaku. Now recovered from his ankle setback, the Belgian was on the scoresheet in midweek at Zenit. Tuchel has admitted he's managing Lukaku's return, granting the centre-forward just over an hour on the night.

And he needs Lukaku to find his best. Not just for the immediate demands, but also for his reputation. Tuchel threw in his lot with Lukaku. At near £100m, the former Inter Milan centre-forward was Tuchel's first significant signing as Chelsea manager. He set out his stall by going for the Belgian. Tuchel needs Lukaku to be a success.

For the moment, however, it's been a mixed bag. Again, the red-hot spotlight has been avoided - at least in England. But from the press in Italy, when Lukaku was fit, you had a more ruthless response. Not the least from his old Inter Milan coach Antonio Conte, now in charge of Tottenham. Indeed, in his role as pundit, Conte didn't so much pull apart Lukaku's game, but turned the spotlight on Tuchel and how he was failing the centre-forward. They were claims that privately irked Tuchel and his upset was relayed back to Conte at the time.

But on Lukaku, as a Premier League performer, the jury is still out. And given the player's success under Conte, how Tuchel manages his No9 is also in play. Again, much like how his team are currently performing, Lukaku's progress is a test for Tuchel's methods. It isn't crisis time. But there are doubts.

The public management of his players. The intensity of matchday. Until just over a fortnight ago, it was working. His team were responding. But now they're stumbling - and just with the Christmas programme upon us.

It isn't a crisis, but things are creaking at the Bridge. It's now a test for Tuchel and whether he can guide his team out of this slump.