Chelsea started their quest to claim the Champions League crown that has remained tantalisingly out of reach with a hard-fought victory against Porto at Stamford Bridge.Nicolas Anelka's strike early in the second half proved decisive against a dangerous Porto side that even threatened to snatch a point as Chelsea survived anxious moments in the closing stagesAnelka fired a powerful finish high past Porto keeper Helton after he had saved his first effort in the 48th minute - and that was enough to give Chelsea three points from their opening Group D game.Carlo Ancelotti's side were efficient as opposed to spectacular as both sides struggled to come to terms with a Stamford Bridge surface made greasy by a torrential downpour.Ancelotti - a two-time winner of the Champions League as manager at AC Milan - has been brought to Stamford Bridge with a brief to bring the trophy to west London. And while this was not a convincing opening to the campaign, he will be relieved to have claimed a crucial three points.And Chelsea were able to achieve it without the talismanic figure of the suspended Didier Drogba against a Porto team who had Fernando sent off in the closing seconds after receiving a second yellow card for a foul on Florent Malouda.Helton kept Chelsea at bay with fine stops from Frank Lampard in the first half and Salomon Kalou after the interval - but Petr Cech was also kept busy and made crucial interventions late on when he saved well from Fredy Guarin and Silvestre Varela.But at this stage of the Champions League, points must be placed above performance in Chelsea's list of priorities, so ultimately this was a satisfactory evening for Ancelotti and his team.Chelsea were without Drogba and Jose Bosingwa as they served suspensions imposed in the aftermath of last season's acrimonious semi-final elimination to Barcelona.And they missed Drogba in particular in a frustrating first 45 minutes in which Chelsea struggled to exert their authority on a Porto side who were providing stubborn, and occasionally adventurous, opposition.The Stamford Bridge surface was treacherous as the game was played in a torrential downpour, and the conditions encouraged Lampard to test Helton with a low shot from 20 yards that the Porto keeper dealt with in less than convincing fashion.Porto were in progressive mood themselves in the opening exchanges and Chelsea keeper Cech looked uncertain as he blocked Hulk's effort with his legs.Lampard, as ever, was prominent in Chelsea's better moments, and he brought a fine diving save from Helton with a header when he got on the end of Branislav Ivanovic's cross as Porto appealed in vain for offside.Chelsea's early promise evaporated as the first half progressed and they were fortunate not to be punished eight minutes before the interval when the unmarked Guarin headed over from only eight yards.Ancelotti's side needed to make a powerful statement after the break - and they did it in the most eloquent fashion when Anelka put them ahead after 48 minutes.Helton did well to block Anelka's initial effort when he was put clear by Kalou, but the striker reacted first to the rebound to steer a finish high into the net from an angle.Ancelotti spent much of the first half pleading for width from his side in an attempt to take advantage of Porto's obvious vulnerability to crosses.And the message got home. although Malouda could only find the side-netting from Ashley Cole's delivery and Helton saved magnificently when Kalou met Ivanovic's cross with a powerful header.Ivanovic should have done better when he stole in on the resulting corner from Lampard, but directed his header wastefully over the top.Chelsea were in charge, but could not rest with only a single goal lead to protect and Guarin gave Stamford Bridge a sharp reminder of the lingering threat with a long-range shot that was gratefully gathered by Cech, before forcing the keeper to save with his legs once more.And Cech was in action again with nine minutes left, coming to Chelsea's rescue with a fine one-handed save from Porto substitute Varela.Porto will have taken encouragement from their performance despite the defeat - but their night ended on a sour note with that red card for Fernando after he flattened Ashley Cole to earn a second yellow card from Austrian referee Konrad Plautz.For Chelsea, it was simply a matter of seeing out the final moments and claiming the victory - something they were able to achieve as the hoped-for march towards the final in Madrid began with three points.Source: BBC