Hitman Nicolas Anelka is singing in the rain

Chelsea found the funds to award Didier Drogba a new contract in the summer, now they need to find some cotton wool to wrap him in so he keeps clear of injuries for the rest of the season.

If ever there was firm evidence of how key the striker is to Chelsea's chance of winning major silverware this term, then this was it.

The build-up to their first Champions League group game of the campaign had been dominated by manager Carlo Ancelotti and Drogba's team-mates insisting they could win without the 31-year-old while he served his three-match ban from the competition. Well they did against the Portuguese champions, but only just.

Ancelotti maintained a brave front after last night's mediocre performance but he must be sweating at the possibility of being without his most potent weapon for a longer period.

Ancelotti knows he won't have Drogba's services in Europe against Apoel Nicosia in two weeks and the Cypriots proved they might not be the weak opposition many predicted with a goalless draw at Atletico Madrid last night.

The striker's six-week absence in the new year, when he goes to play for the Ivory Coast in the African Nations' Cup, has grown in significance in terms of Chelsea's title hopes. They looked impotent for long periods against Porto - without their main talisman leading the line, they pose half the threat.

So Ancelotti must be praying that Drogba doesn't pick up any serious injuries because with the club banned by FIFA from making any transfers, they don't look strong enough to cope without him on a regular basis.

Against Porto, Ancelotti had Nicolas Anelka leading the line with Salomon Kalou offering support but while the former showed flashes of inspiration, the latter was a disappointment.

Kalou may point to setting up Anelka's winning goal in the second half, yet it was one bright moment in 77 minutes of mediocrity before he was replaced by Juliano Belletti.

Kalou is considering whether he will sign a new contract - perhaps Chelsea should decide whether he is still worthy of one. He has been at the club for three years and has shown little improvement from the inconsistent player who first arrived on these shores from Feyenoord. Kalou is also set to join up with Drogba in the Ivory Coast squad in January, yet little fuss has been made at that prospect.

His deficiencies were exposed after Anelka had put the home side in front and Chelsea failed to keep possession as Porto applied intense pressure.

The 24-year-old lost the ball on many occasions and when it came to physical challenges, he was too easily brushed aside. He also wasted a great chance to make the victory secure when he had a free header from Branislav Ivanovic's cross but his effort gave Porto keeper Helton a chance to palm the ball to safety. Anelka certainly showed him how it should be done in the 48th minute, when he cleverly chipped the ball into the near corner after his first effort had been well saved by Helton.

Captain John Terry, who bravely fought on after being knocked unconscious in an early clash with Porto captain Bruno Alves which left him requiring lengthy treatment, is fully aware of the need for the other forwards to produce when Drogba is absent. He believes, in Anelka, they have someone who can do just that. He said: "Everyone was talking about Drogba being out and it's up to the players like Nicolas to step up to the plate, which he did.

"He proved his worth. He was top scorer in the Premier League last season. Didier and him are a great threat together but when Anelka plays alone he shows what a great finisher he is."

Porto will still wonder how they failed to get a point, especially after creating so many chances. Freddy Guarin's header looped just over the bar, while keeper Petr Cech made some fine stops. The match was played in torrential rain, which affected the playing surface. Terry, however, told his team-mates the bad weather couldn't excuse a disappointing performance.

He added: "The conditions affected us a little bit but they didn't give it away as much as us. You can half blame the conditions but I blame our sloppy passing at times as well.

"They're a good side and going to pose a threat in the group."