David Luiz to get early test - but Chelsea still lacking John Terry replacement

Chelsea knew they needed defensive reinforcements in the recently closed transfer window, they just didn't know quite how soon they would need them – until now.

The sneaking in of David Luiz and Marcos Alonso through the aperture of a barely ajar window on deadline day seemed to be evidence of a club that attempted to chase down a number of targets, and failed to get pretty much all of them. Both players do clearly add something to Antonio Conte's squad, but it is difficult to say exactly what. Time will tell whether these will be trusted regular servants, or just providers of a little depth to a squad that even with them looks quite shallow.

Both were benched for the weekend trip to Swansea: common sense, with the prevailing wisdom being that defenders operating in a system take longer to acclimatise to new surroundings than the natural flair players one might use up front.

That learning curve may have been allowed to continue for several weeks, were it not for the mishaps that befell both of the Blues' centre-halves at The Liberty.

Gary Cahill's terrible indecisiveness, in the lead-up to Swansea's second goal, was merely mitigated, rather than being completely excused, by referee Andre Marriner's failure to spot a foul by Leroy Fer on the defender. Meanwhile, John Terry's late ankle twist, which saw him unable to play out the final moments of the game as anything other than a passenger, will leave him battling fitness tests to jettison the crutches on which he hobbled out of the stadium.

Conte is still without Kurt Zouma – in the latter stages of recovery from the anterior cruciate ligament injury that has sidelined him since spring. And, so, with the biggest test so far this season about to descend – with the arrival of Liverpool at Stamford Bridge on Friday night – Conte finds himself dealing with question marks over both pillars of his thus far preferred central defensive pairing.

This squad is built for options: there are men who can cover more than one base. Branislav Ivanovic can play in the middle, but would you risk him in an unsteady position, when that will also almost certainly mean gambling with an Alonso debut at full-back? And then there is Luiz.

We all know, some of us all too well, the pros and cons of the Brazilian's ball-playing game. He helps switch the play from defence to attack well, and is able to distribute the ball in a way Chelsea have tended to lack under Conte's system – hence the regular, late incorporation of smart-passing Cesc Fabregas into games. But he is a defensive wildcard – prone to lapses, and often the quality of his performances is dictated by whoever he is paired with at the back.

Is Cahill and Luiz the right answer against Daniel Sturridge and Saido Mane? The brutal truth is it might be the only answer, and that could well be the case for some time to come, depending on the severity of Terry's injury.

Those two players have a peculiar trait in common: they both tend to use as a crutch their central defensive partner. They both have leadership skills, after a fashion, but not in a style capable of filling the vacuum left by Terry, should he not be there. The risk assessment thrown-up by that particular pairing is not a brief piece of work, but it is one that Chelsea may have to get used to reading as the season draws on.

Blues, of course, have flourished against Liverpool before with a makeshift centre-half pairing: they fielded Ivanovic and debutant Tomas Kalas at Anfield in the much celebrated 0-2 win which robbed the Reds of what looked like a certain title triumph in 2014. But both of those players were more solid and functional than any potentially available pairing might be from the present suite of skills.

All of this is chickens coming home to roost, of course, as for the umpteenth window the club has failed to adequately address the issue of succession planning for Terry, who is surely in his last campaign at Stamford Bridge. Thus it should be noted that these defensive dilemmas are merely the start of something that could be a major issue for the club for some time yet.

Chelsea, for now, have bodies at the back, but what they really lack is a rock, capable of carrying forward Terry's mantle in his absence.