By Phil McNulty

Alex is mobbed after scoring Chelsea's third in Norway

Chelsea cruised into the Champions League knockout stages with an easy win against Rosenborg in Norway.

Didier Drogba set the platform with two close-range finishes inside the first 20 minutes as Avram Grant's side dominated from the start.

Alex added a third before half-time with a low free-kick that somehow crept past Rosenborg keeper Lars Hirschfeld.

Joe Cole rounded off the scoring in the 73rd minute after Michael Essien's shot had been blocked by Hirschfeld.

News conference: Chelsea captain John Terry

606: DEBATE No fresh injury worries, qualification and group winners. Lovely! Chels' - in the blood

Drogba had already threatened twice before giving Chelsea the lead after eight minutes.

Ashley Cole's long-range shot was only partially blocked by Hirschfeld, and Drogba pounced on the rebound to lash an unstoppable shot high into the net.

And he got the second Chelsea's blistering opening spell fully deserved after 20 minutes, but much of the credit must go to Shaun Wright-Phillips.

He won a tackle in midfield and embarked on a mazy run before feeding Essien, who scuffed his shot, but once more Drogba was first to react to turn in from close range.

Chelsea were controlling the game with almost embarrassing ease, and it was no surprise when Alex added a third for them five minutes before the interval, his low free-kick from 30 yards somehow squirming past Hirschfeld.

The pattern continued after the break, with Wright-Phillips coming close to adding a fourth after 52 minutes, turning Drogba's pass against the bar with Hirschfeld beaten.

Chelsea keeper Carlo Cudicini finally got some action on a freezing night after 65 minutes when he turned over a rising drive from Marek Sapara.

The fourth was inevitable, and came with 17 minutes left, Joe Cole turning in another rebound when Hirschfeld could only block Essien's shot.

Rosenborg: Hirschfeld, Stoor, Kvarme, Riseth, Dorsin (Basma 85), Skjelbred, Tettey, Traore (Strand 56), Sapara, Iversen, Kone (Konan 63).
Subs Not Used: Hansen, Koppinen, Storflor, Nordvik.

Chelsea: Cudicini, Belletti, Terry, Alex, Ashley Cole, Makelele, Wright-Phillips (Kalou 68), Essien, Lampard (Pizarro 76), Joe Cole, Drogba (Shevchenko 68).
Subs Not Used: Hilario, Obi, Bridge, Ben-Haim.

Goals: Drogba 8, 20, Alex 40, Joe Cole 73.

Att: 21,582

Ref: Olegario Benquerenca (Portugal).