Chelsea ensured first place in Champions League Group D is ours after another clean sheet helped us on our way to a slender victory at Porto.

It was both our fourth win, and fourth clean sheet from five group games this season, and wraps up top spot ahead of tonight's hosts, who might claim they deserved a draw.

The win came courtesy of a close-range Nicolas Anelka header midway through the second half, after which Porto pressed for an equaliser but could not beat Petr Cech, who made a pair of impressive saves.

With qualification into the knockout stages already secured for both sides, this game would go some way to deciding who would top the group. Chelsea went into the contest three points clear, owing to our 1-0 victory over Jesualdo Ferreira's side at Stamford Bridge back in September.

Since then both sides had won each of their other three games and by avoiding defeat tonight, the Blues would have top spot sewn up.

Carlo Ancelotti went with the five players he had indicated would play in yesterday's press conference, so Branislav Ivanovic, Ricardo Carvalho, Yury Zhirkov, Michael Ballack and Deco came in, while the Italian also surprised with his selection of Didier Drogba, who he had suggested would be left on the bench.

Even without Frank Lampard, Jose Bosingwa and Ashley Cole, it was a strong and attacking-looking Chelsea line up, so it was a little surprising that it took until the 15th minute for Porto keeper Beto to be worked.

Anelka was afforded the time and space to shoot outside the area, striking a decent effort straight down the goalie's throat.

A moment later Drogba had an effort deflected over for a corner, allowing the home support an opportunity to warmly welcome Deco back to northern Portugal, a gesture to which the midfielder responded with an appreciative clap.

On 20 minutes Porto had their best opportunity of the first half, Cech pushing a Fernando Belluschi shot into the path of Falcao, who couldn't beat the giant Czech from eight yards.

Belluschi, who hit the crossbar at Stamford Bridge as an Olympiacos player two seasons ago, clearly likes to let fly.

Just before the half-hour mark, he had another crack, cutting inside onto his right foot and bending a superb effort around and over Cech, yet once again finding the woodwork, while seconds later Falcao worked the goalkeeper again with a similarly rangy effort.

That was the last notable action of a competitive yet cautious first half, and Chelsea fans who had turned out will have been hoping for something positive in the second half to warm them on a cold night.

Porto's Fernando was yellow-carded for a lunge on Drogba five minutes into the second half, presenting a shooting opportunity 30 yards from the Porto goal, to the left of the box. Drogba took it himself but shot straight into the wall, and so still the fans shivered.

Finally the moment came on 68 minutes, and it was Anelka who netted his third European goal of the season.

It was a simple finish, nodding into an empty net from a couple of yards after Malouda had picked him out after reaching the bye-line.

Deco was replaced by Joe Cole with 15 minutes to go, receiving a huge ovation from the Porto fans for his contribution while at their club, a time that included Uefa Cup and Champions League successes.

On the field Porto weren't giving up, Falcao heading just over and sub Hulk shooting straight at Cech inside a five-minute period, but this isn't a Chelsea side that concedes goals freely, and once again there would be a European clean sheet, making it four from five games as we marched on with another win.

Next up for Ancelotti and his men is the crucial London derby at Arsenal on Sunday, we look in good shape for another successful away day.

Porto(4-3-3): Beto; Sapunaru (Farias 79), Rolando, Bruno Alves (c), Pereira; Belluschi (Guarin 70), Fernando, Raul Meireles; Varela (Hulk 59), Falcao, Rodriguez.
Booked Fernando 50, Meireles 78

Chelsea (4-diamond-2): Cech; Ivanovic, Carvalho, Terry (c), Zhirkov; Mikel, Ballack (Essien 67), Malouda, Deco (Joe Cole 75); Anelka, Drogba.
Scorer Anelka 68
Booked Ballack 57

You can watch the full 90 minutes of the game on Chelsea TV from midnight tonight.