Murray withdraws from Cincinnati Masters with eyes on US Open
The Scottish world number one has been out of action since losing in the quarter-finals of Wimbledon, and could lose top spot to Nadal or Federer.
World number one Andy Murray will not compete in the Cincinnati Masters next week due to an ongoing hip injury, but hopes to play at the U.S. Open in New York later this month, he said on Wednesday.
Murray: "New York is the aim"
"Unfortunately I won't be playing in Cincinnati as I continue my recovery," Murray said in a statement.
"I always enjoy playing there and I look forward to returning next year. I'm continuing to work hard on the court with the aim of being in New York."
Murray's decision has hampered his hopes of winning a second U.S. Open title as he has yet to play in any hardcourt tournaments in the lead up to the final major of the year.
He has been out of action since losing in the quarter-finals of Wimbledon in July.
Nadal could take number one spot
The 30-year-old Briton has held the number one ranking since November of last year, but that may not last much longer.
Murray's absence at the Rogers Cup in Montreal this week means Rafael Nadal could take the top spot should the Spaniard advance to the semi-finals in Canada.