Here, however, was Havertz standing over a re-taken penalty with tension at such a boiling point around Stamford Bridge that Potter simply could not bear to watch as the German stepped forward.

The thunderous roars and the bearhugs from his backroom staff delivered the good news and Chelsea went on to close out a win that was, without question, the finest night of Potter's troubled time at Stamford Bridge.

Make no mistake, the 47-year-old has not only struggled to convince many Chelsea fans of his suitability to tackle this occasionally dysfunctional football beast but has also felt the fierce heat of their criticism since he arrived from Brighton to succeed Champions League winner Thomas Tuchel in September.

Potter faced a potentially defining week only months into his reign after a home defeat by strugglers Southampton and another away at Tottenham turned up the volume on whispers about his future.

Chelsea's new owner Todd Boehly, whose remarkable spending spree only added to the pressure and expectations surrounding Potter, has always insisted he was sticking by his manager but any slips at home to Leeds United and then Borussia Dortmund would have put that faith to the severest test.

Instead, a scrambled win over Leeds was followed by Chelsea's best performance under Potter and now, with a Champions League quarter-final to look forward to, at least some of the clouds have rolled away.

Chelsea have now progressed from five Champions League knockout stage ties after losing the first leg, the joint-most of any team in the competition's history

And for Potter, he will hope this night and the celebrations that followed it on and off the pitch will be a launchpad for stability and improvement as well as the all-important connection with Chelsea's fans.

Potter has been criticised for being too passive as Chelsea manager - his calm demeanour on the touchline portrayed as him being some sort of soft touch, something he understandably denied with a passion.

This was a different Potter. A different Chelsea.

In the first few minutes he was windmilling his arms to get Chelsea's fans behind their team and he was animated throughout. Passive? Not here.

And at the final whistle, Potter's beaming face illuminated Stamford Bridge as he marched towards the Matthew Harding Stand before delivering rousing fist pumps in the manner normally associated with Liverpool manager Jurgen Klopp.

Potter then blew kisses towards the stands as the frustrations and uncertainties of recent weeks were transformed into an outpouring of joy.

And owner Boehly, whose riches have bankrolled this seemingly money-no-object new Chelsea era, looked down on it all with what appeared to be a mixture of elation and relief.

Chelsea's two home wins will not send all the troubles floating away but this Champions League victory will do wonders when measured in how supporters feel about their manager. These are the sort of victories that boost the credibility and buy time.

Chelsea scored more than once in match for the first time in 13 matches in all competitions, since beating Bournemouth 2-0 in the Premier League in December

There is still a desperately poor Premier League placing of 10th to be addressed and it still appears that Chelsea may have to win the Champions League to play in the competitions next season. Odds against, but Chelsea have done strange things in the Champions League before.

Chelsea looked at home with the outstanding pair of Reece James and Ben Chilwell performing heroically in defence and as an attacking threat - the latter also making Potter's former Brighton player Marc Cucurella look more comfortable than he has on many occasions.

And there was no doubt Chelsea's players were performing for their manager as they tore into tackles from the first whistle, a period which also included an outstanding save from keeper Kepa Arrizabalaga as he dived to save a free-kick from Marco Reus.

Potter and Chelsea must now cash in on this sudden surge of momentum because the doubts will resurface if they revert to their more normal form of this season at struggling Leicester City on Saturday.

This was the sort of night Potter had in mind when he exchanged the stability and calm progress he oversaw at Brighton for what can be the madness of Chelsea - namely scenes of celebration around Stamford Bridge after a landmark Champions League win.

Now Potter has had the taste he will want more and hope the same applies to his re-invigorated Chelsea players.