Chelsea overcame determined Danish side FC Nordsjaelland to earn a first Champions League group stage victory.
The champions went ahead when Fernando Torres and Frank Lampard combined to set up Juan Mata to slot home.
Nordsjaelland rattled the visitors and Joshua John sent a shot just wide and had a strike palmed on to the post.
But David Luiz scored with a free-kick, Mata added his second with a left-foot shot and Ramires tapped in to give the scoreline a slightly flattering look.
Chelsea had shown commendable resilience but had also had lived dangerously, with their failure to add to their early lead encouraging their largely unknown and unfancied opponents, who were playing first ever game on home soil in the Champions League.
Almost immediately, Oscar crossed for Moses at the far post but, just as the winger appeared set to nod in, Nordsjaelland centre-back Jores Okore flung himself across to force the effort against the post.
Okore had to have treatment after the clash and, despite coming back on with a bandage around his head, he was an inspirational presence for his side with his all-action style.
Nordsjaelland gradually shook off the nerves and began to play a style of passing football that was easy on the eye and meant the visitors had to be wary.
Chelsea left-back Ashley Cole gave the ball away to Dutch striker John, who has eight goals in seven league appearances so far this season, but he sent an ambitious long-range shot well off target.
The home side’s weakness was an uncertain defence and, after Torres had a shot saved having picked up Ivan Runje’s miscued headed clearance, Chelsea deservedly took the lead through Mata.
Torres caught Enoch Adu in possession and laid the ball across to Lampard, whose deft first-time pass between two defenders was met with a confident finish by Mata past keeper Hansen.
An alert Hansen then denied Torres but Chelsea failed to extend their lead and were almost punished.
John arrowed a shot just the wrong side of the post before Mikkel Beckmann latched on to Okore’s lofted pass, only to send a 10-yard header high.
A Nicolai Stokholm 20-yard strike stung the palms of Cech, who also produced a superb save to fingertip another John effort against the post.
However, a lovely dipping Luiz free-kick went in off the post and signalled a late flurry of Chelsea goals.
Some clever passing from the visitors ended with Mata sidefooting in before Oscar crossed for Ramires to tap in after 89 minutes.