Nicolas Anelka proved Chelsea can survive and prosper without banned Didier Drogba as the France international settled their opening Champions League qualifying game against Porto with a second half winner.
Anelka, given the task of filling a lone role in attack in the absence of the suspended Ivory Coast international, struck three minutes after the interval to dispel any lingering doubts that Chelsea cannot cope without the talismanic Drogba.
Drogba is banned for the first three Group D games following his foul-mouthed rant after the semi-final defeat to Barcelona last season, but Anelka, as he has so often done in the past, made the most of his opportunity to shine.
Chelsea were good value for their victory despite the marginal scoreline and turned on the style when torrential rain threatened to make quality football something of an impossibility.
Porto, surprisingly, were equally adept in the soaking conditions and with better luck in front of goal could have drawn first blood.
A 20-yard drive from the impressive figure of the aptly nicknamed Hulk bounced off Petr Cech's knees in the fifth minute with the Chelsea goalkeeper totally unaware of the power contained within the shot.
But Chelsea should have been in front two minutes later. The fact they did not capitalise on a fine cross from Branislav Ivanovic was purely down to the heroics of Porto keeper Helton, who punched away Frank Lampard's header.
Porto also demonstrated they were more than capable of mixing the sublime with the physical when Bruno Alves poleaxed John Terry with a clear elbow.
The home side continued to live dangerously with Cristian Rodriguez flashing an angled drive just wide of the far post in the 13th minute.
But the home side should have gone ahead in the 19th minute when a smart move involving Florent Malouda and Lampard set up Anelka.
But the France international shot straight at Helton when it seemed easier to score.
Fredy Guarin gave Chelsea another scare in the 37th minute when he managed to climb higher than Terry - but his header was just inches over the bar.
But the English side broke the deadlock in the 48th minute when Kalou, having slipped on the wet turf, poked the ball through to Anelka on the edge of the 18-yard area.
The France international looked to have squandered another chance when Helton saved his initial shot but the ever alert Anelka collected the rebound and sent his second effort into the net at the near post.
Chelsea were now on top with Michael Essien, whose passing had been as atrocious as the weather in the opening half, finally getting to grips with his surroundings.
Malouda should have increased Chelsea's lead in the 54th minute but he headed Ashley Cole's cross into the side-netting.
Four minutes later Helton produced another stunning save to deny Kalou but Chelsea then lost their purpose and midfield superiority.
It was now Cech's turn to be the star goalkeeper as Porto turned the screw in the final 20 minutes.
For the first time in the game, Carlo Ancelotti's side looked distinctly vulnerable as Porto launched a succession of counter-attacks.
They almost equalised when Guarin tested Cech with a powerful drive in the 75th minute and the Chelsea goalkeeper then produced another superb save to prevent substitute Silvestre Varela from finding the net with an angled drive.
It was an anxious time for the home side and Ancelotti was quick to see the danger, taking off Kalou and replacing him with defender Juliano Belletti.
It was a change aimed at stemming the flow of Porto's classy attacks - and for a while it succeeded.
But Chelsea's old failings began to surface once more as the game moved into injury-time.
The midfield lost their shape and the ball was given away cheaply. Indeed the panic stations in the home defence had echoes of the final moments of that heartbreaking semi-final against Barcelona last season.
But Porto did not have any one with the same shooting skills as Barca's Andres Iniesta and when Fernando was red-carded for a lunge on Cole, Porto's cause was lost as Chelsea hung on to record a nervy victory and Ancelotti's sixth straight win at the helm.