LONDON (AP) For Andy Murray, the road leading back to the ''Big Four'' remains winding and tortuous.
Following an excellent autumn run that helped him qualify for the ATP Finals, the former U.S. Open and Wimbledon champion was brutally brought back to earth by Roger Federer, his season ended by an embarrassing 6-0, 6-1 loss in his final round-robin match at the O2 Arena on Thursday.
Murray bowed out of the elite tournament with just one win, over debutant Milos Raonic, and two straight-set defeats to Federer and Kei Nishikori: A mediocre record for Murray, who was running with Novak Djokovic, Rafael Nadal and Federer until a year ago.
Murray, who missed the event last year after undergoing surgery on his back, went through a difficult season during which he split with coach Ivan Lendl. He slipped to 12th in the rankings in September and his return to top form is taking longer than he expected.
''It's been a hard year,'' Murray said. ''I'll look back on it, and I've definitely learnt a lot this year about my body, what it's like to come back from a tough, tough surgery. It's not easy. I'll spend more time, I always spend a lot of time, but more time taking care of my body, making sure I don't have to go through that again.''
His back problems solved, Murray came back strongly during the second part of the season under the helm of new coach Amelie Mauresmo, grabbing three titles to qualify for the ATP Finals for the seventh straight year. But his improvement should not end there if Murray is to regain his status among the elite.
''Well, after tonight that's quite clear,'' he said. ''Quite a long way from that level.''
Federer moved to 12-11 in head-to-heads with Murray, but the Scot's last victory over the 17-time Grand Slam champion dates to the 2013 Australian Open. Murray is 0-9 against Federer, Djokovic and Nadal this season.
''But a lot can change in a matter of weeks and months in tennis,'' Murray said. ''Roger is a good example of that. Last year, he was having some struggles and some tough times with his body and whatnot. A lot of questions were asked about him. He's responded and gone into the last tournament of the year with an opportunity to get to No. 1.''
Federer said Murray's preparations for next season will be crucial.
''You just tend to be up and down, especially against the top players,'' said Federer, recalling his own experience with injuries. ''There's just that little bit of doubt, maybe that you need to play unbelievably well, and the other guy you hope he doesn't play his best. Maybe he has this kind of confidence issues. Every point is complicated. Every day is complicated.''