Always one of the most dangerous players in both singles and doubles, she was one of the true double threats on the WTA. But after some major struggles with injury in 2009 and difficult times trying to recapture a perfect balance, Katarina Srebotnik has decided to retire from singles and focus on doubles.

By the end of 2008, Srebotnik - whose all-court game had brought her four career singles titles and 20 career doubles titles on the WTA - was among the upper echelon in both disciplines, finishing the year at No.20 in singles and No.4 in doubles. But Achilles and shoulder injuries kept her from returning to the court until the US Open in 2009 - 10 months later - and though she salvaged the year with her 21st doubles title in Linz, it set the stage for a crossroads.

"I practiced very hard in the off-season in 2009 to prepare to play my best in singles and doubles in 2010. My career goal was always to do well in both," Srebotnik said. "Because I was still doing very well in doubles, I used my special ranking in singles at bigger events, so I could play doubles there too."

By the end of the 2010 season, Srebotnik was back in the Top 10 in doubles, following stellar results with Kveta Peschke (including two Premier-level titles and seven more finals, including the French Open and WTA Championships). But it was a different story in singles: she won three matches in 10 events, five of her 10 losses being close three-setters - matches she used to win.

"I was in a situation. I was No.228 and couldn't even make the qualies of the US Open," Srebotnik said after her last singles match, a loss to Zheng Jie in Montréal in the summer. "Everything was pointing to a new direction."

Some advised her to play the smaller tournaments in singles to build her ranking back up, but that strategy would have left half of her career goal under-fed.

"The only way to give both singles and doubles a chance was to play the bigger tournaments. I've proven in the past I can beat the top players in singles, and I was already at the top level in doubles again, so that would mean I'd sacrifice playing at the top level of doubles. Also, my goal for singles wasn't just to get back to the Top 70 or something - if I was going to get back to the top level in singles, I had to play the bigger tournaments and see what would happen.

"But at age 29 and after the injuries I've had, my body wasn't holding up in the tough moments in matches, especially in the three-setters. My shoulder would get stiff, then the serve dropped, then the whole game. It was telling me it couldn't hold up for the long singles matches - but it's perfect for doubles."

There is also a logistic problem with the disparity in singles and doubles ranking for a player. "I would have to play a lot of qualies to get into main draws, but you play those on the weekends, and what if I was in the doubles final the week before? Would I be disappointing my doubles partners? It would be too tough."

So, having achieved a 2010 year-end ranking of No.6 in the world in doubles and No.312 in singles, one of the greatest double threats on the WTA of the last decade will become one of the greatest doubles threats of the next.