Chelsea put their Premiership challenge back on track with a comfortable win against Portsmouth at Stamford Bridge.
Former Southampton defender Wayne Bridge sent old arch-rivals Pompey on the slide with a second-half strike.
Frank Lampard sealed the victory with a second - and Geremi provided the final flourish with a stunning volley.
Chelsea turned on the style after the break to deliver the perfect tonic after the Boxing Day shock at Charlton.
But it was a day of struggle for Portsmouth after stubborn first-half resistance, and Harry Redknapp's side remain without a win away from home this season.
Ranieri dropped captain Marcel Desailly to the bench and handed the armband to John Terry after the defensive calamity at Charlton.
It was one of five Chelsea changes - and Portsmouth boss Redknapp sprang a surprise of his own by resting veteran Teddy Sheringham, leaving him on the bench.
Ranieri was also without goalkeeper Carlo Cudicini, who suffered a thigh injury at The Valley and was replaced by Neil Sullivan.
Chelsea were struggling to shake off their festive lethargy early on, but an exchange between Lampard and Adrian Mutu lifted the mood, with the Romanian firing over the top from 20 yards.
But Pompey had an opportunity of their own when Yakubu Ayegbeni broke clear in the 13th minute but fired wastefully wide
Mutu was the danger man again when he saw a shot on the turn deflect off Portsmouth captain Arjan De Zeeuw just over goalkeeper Harald Wapenaar's bar.
65 mins: Wayne Bridge breaks the deadlock for Chelsea
73 mins: Frank Lampard seals the points with Chelsea's second
82 mins: Geremi strikes Chelsea's third with a brilliant volley
Yakubu was the culprit again on the half-hour when he broke clear but shot tamely at Sullivan.
Lampard almost broke the deadlock five minutes before the interval when a long-range drive cannoned off the woodwork to safety with Wapenaar beaten.
Yakubu turned creator after 47 minutes when he escaped Mario Melchiot's attentions and crossed for Steve Stone, whose near post shot was clawed to safety by Sullivan.
It was Stone's final contribution as he limped off with what looked to be a hamstring injury and was replaced by Sebastian Schemmel.
The deadlock was finally broken after 65 minutes, from the unlikely source of Bridge.
He took a pass from Geremi and fired home left-footed from 18 yards for his first league goal for Chelsea, with Wapenaar perhaps at fault.
And Chelsea sealed the points eight minutes later when Lampard provided a sweet finish after more delightful approach work from Mutu.
Portsmouth's resistance was broken, and Chelsea added to their agony in spectacular fashion with a dipping from Geremi eight minutes from time.
Chelsea: Sullivan, Melchiot, Terry, Gallas, Bridge, Geremi,
Makelele, Lampard, Gronkjaer, Mutu, Gudjohnsen.
Subs Not Used: Johnson, Desailly, Hasselbaink, Cole, Ambrosio.
Portsmouth: Wapenaar, Primus, Stefanovic, Zivkovic, De Zeeuw,
Stone (Schemmel 54), Yakubu (Taylor 85), Hughes, Berger,
O'Neil (Robinson 85), Roberts.
Subs Not Used: Sheringham, Srnicek.
Referee: G Barber (Hertfordshire).