A first-half strike from Nicolas Anelka gave Chelsea a 1-0 win over Bolton and sent them four points clear at the top of the Premier League.[LNB] But it was evident from the laboured performance by Carlo Ancelotti's side that the title nerves are beginning to take hold.[LNB]The Blues had to wait until the 43rd minute to break down a stubborn Bolton side who almost snatched a draw in the closing stages.[LNB]Manchester United boss Sir Alex Ferguson insists the title is Chelsea's to throw away and, judging by the anxiety on show at Stamford Bridge, the run-in promises to be a thrilling affair.[LNB]There was little evidence that Chelsea would struggle to overcome Owen Coyle's side when left-back Yury Zhirkov created a chance for the home side in the fifth minute.[LNB]The Russian pulled the ball back for Ivory Coast striker Didier Drogba who sent his curling shot over the crossbar.[LNB]Bolton's defence was almost caught out again moments later but Drogba was given offside as he tried to beat Jussi Jaaskelainen.[LNB]In the seventh minute, Chelsea had a scare when captain John Terry required lengthy treatment on his ankle following a collision with Matthew Taylor. But the England defender was able to continue without any ill effects.[LNB]The Blues had lost their early impetus, though, and Bolton caused problems for the home side when Petr Cech failed to collect a cross from Chung-yong Lee.[LNB]Taylor almost profited from Cech's hesitation but the Czech Republic international quickly regained control of the ball before the Bolton midfielder could strike.[LNB]Zhirkov was in the wars in the 18th minute when he went down following a collision with Bolton striker Kevin Davies. The left-back required a hefty bandage on his head to stem the flow of blood before being allowed to continue.[LNB]Chelsea almost went in front in the 25th minute when Jaaskelainen punched Drogba's free-kick straight at Salomon Kalou. But, luckily for Bolton, it bounced off his head and wide.[LNB]The hosts were becoming more and more frustrated by Bolton's battling rearguard and that increased in the 37th minute when Drogba sent another free-kick wide of the target from 20 yards.[LNB]Zhirkov was asked to leave the pitch in the 39th minute by referee Lee Probert because he was still losing blood from his head wound.[LNB]It was clear the Russian defender's injury required stitches and Chelsea continued with 10 men - Frank Lampard taking over Zhirkov's position until he re-appeared in the 41st minute.[LNB]The breakthrough came in the 43rd minute when Drogba's cross was headed home from inside the six-yard box by Anelka.[LNB]It was the France international's first goal in 14 games for the Blues in a barren spell lasting just over two months.[LNB]Moments later Kalou tried to increase Chelsea's lead but his 20-yard shot was well wide of the target.[LNB]Chelsea's opening goal failed to liven up their performance as the second half began.[LNB]Bolton enjoyed much of the possession and the home side looked decidedly subdued.[LNB]Chelsea had even resorted to lumping high balls in the general direction of Drogba but it was a fruitless tactic.[LNB]Kalou wasted a great chance to put the game beyond Bolton in the 54th minute when Drogba put his Ivory Coast team-mate through on goal.[LNB]Kalou only had Jaaskelainen to beat but his shot was saved by the Bolton goalkeeper.[LNB]But it was a rare chance for the home side, who then survived a penalty appeal when Terry appeared to use his arm to divert a cross from Lee into Cech's hands.[LNB]Zhirkov forced Jaaskelainen into another fine save when he collected a return ball from Lampard and thumped a volley straight at the Bolton keeper.[LNB]Anelka was replaced by Florent Malouda midway through the second half.[LNB]A superb 40-yard pass from Alex in the 75th minute allowed Kalou to get free of the Bolton defence yet again but his angled drive was well saved by Jaaskelainen.[LNB]Three minutes later Lampard almost sealed victory when his 20-yard drive cannoned back of the inside of the post.[LNB]Six minutes from time Bolton substitute Johan Elmander was inches away from equalising when he headed a cross from Taylor just wide.[LNB]It was, though, the last nervy moment for the hosts, who hung on to move a step closer to achieving the league and FA Cup double.