Tim Henman believes his Davis Cup performances for Great Britain could have damaged his chances of qualifying for the end-of-season Masters Cup.
Henman had spent most of the season in the top seven of the Champions Race, but slipped out in the final week of qualifying after losing in the third round of the Paris Masters.
The British number one played and won two singles and a doubles rubber for his country in their 3-2 win over Thailand even though he had struggled with a shoulder injury since August.
But the 27-year-old, who has refused the opportunity to be second reserve at the Shanghai event next week, says he may have returned to action too soon.
"The Davis Cup tie against Thailand was very important to me but came at a bad time and set me back a little bit," said Henman.
"Usually the indoor season is very good to me in terms of results, but this year I found it hard to compete while serving at three-quarter pace, which is understandable.
"While I've tried hard to be as positive as possible in pursuit of my goal to reach the Masters Cup, it's been very difficult to compete week-in week-out knowing I couldn't give my best due to the injury."
Henman, who has also hinted that he may be forced to miss the Australian Open in January, says he is now looking ahead to concentrating fully on finally shaking off the shoulder injury.
"I'm going to try and make sure I do whatever I can to try and get my shoulder right before the start of next season," added Henman.
"I'm currently talking to various medical experts to see what the best course of treatment is in order to speed up the recovery process while I'm resting."