Andy Murray beaten by Kei Nishikori in straight sets at Barclays ATP World Tour Finals But Murray was also skittish in his first match in Britain since his equally passive performance in the Wimbledon quarter-final against Grigor Dimitrov, another of the young guns who have threatened the established order this season. One wonders if he might be feeling the pressure of expectation more strongly since becoming the Wimbledon champion almost 18 months ago. It is also possible that he arrived at the O₂ with some concerns about the way the crowd would react to him after his controversial tweet in favour of Scottish independence two months ago - although, in fact, he received a warm reception. Given that Murray came in with a 3-0 record against Nishikori, we had expected this to be his most straightforward outing of the group stages. Certainly, he cannot expect life to get any easier from here. He also has to play Roger Federer, a man who has beaten him in all three of their previous meetings at the O₂, and last week's Paris finalist Milos Raonic. Nishikori has a fleet-footed, well-balanced game, but he also possesses the weakest serve of any of the eight men at this event, and was particularly out of sorts on this front on Sunday. You are unlikely to serve so many double faults on an indoor court unless you are suffering from nerves. As one of the sport's consummate returners, Murray should have been cashing in on so many freebies, but his timing was horrible in the first set. Nishikori's early wobbles extended beyond the serve to a number of erratic forehands, but he settled as the match went on and began to play with increasing authority. To return to that not-so-trusty second serve, Murray won just 27 per cent of those points - which he raised in the press conference. It also underlined the observations made in Sunday's Telegraph by Greg Rusedski. According to the former US Open finalist, Murray has been throwing the ball up in a different position this year, and consequently failing to find his usual heavy top spin. When this point was put to Murray on Sunday, he replied that he had not made any conscious changes to his action, since the serve was one of the shots that did not create any problems for his cranky back. But he did admit that "at the end of the year, what I will do is actually have a look at some video of [the way I played] before my surgery and now to see if things have evolved or things have changed my game." Unless Murray can find more dynamism on Tuesday, his season could be over by Thursday. Realistically, he needs to win both his remaining matches to qualify for the semi-finals, and the first one will be against Raonic, the heavy-hitting Canadian who lost 6-1, 7-6 to Federer in Sunday's evening match. Like Nishikori, Raonic is making his maiden appearance at the O₂, and he also got off to a flaky start, conceding a pair of service breaks in the opening exchanges. For a man with a 145mph cannon, that was careless indeed. But Raonic then lifted his level and played some dangerously powerful tennis in the second set. He forced four break points, only to see Federer save them all with aplomb, and sweep the ensuing tie-break 7-0. Still, the debutant showed enough quality to suggest he will be no pushover for Murray on Tuesday night.