Andy Murray said match fitness will be the key to the remainder of his season after reaching the second round of the ATP/WTA Cincinnati Masters on Monday.
The two-time champion at the US Open run-up event reached the second round with a gruelling 7-6 (7/3), 5-7, 7-5 win over fellow veteran Stan Wawrinka.
After half a decade of injury problems including a pair of hip surgeries, the Scot knows the remainder of his season, and career, will depend on his physical state.
"Physically I felt pretty good for the last few months, but in a lot of the tournaments I've lost in the second round," he said.
"I've not had that opportunity to have a really good tournament and then maybe take a break and rest.
"I hope I can get to that level again where I'm consistently getting to the latter stages of events, and therefore, we will be able to plan and schedule my tournaments better."
The three-time Grand Slam champion was tested to his limit over almost three hours against Wawrinka, like himself still recovering fully from long term problems (foot, knee).
"There have been some good moments this year, but it's not been easy these last few years to stay fit and healthy and play enough tennis to build confidence, get robust enough to compete week in, week out," Murray said.
"It's positive that I got to play more matches this year. Hopefully I can continue that through the end of the season."
Murray's comeback effort this season has included finals at Sydney in January and on grass in Stuttgart two months ago.