• Former world No1 tells fans to wait for important news on Wednesday • Serb has slipped to No63 in rankings after injury-plagued 2016

Ana Ivanovic has fuelled rumours of retirement by announcing she will reveal “important” news on Wednesday. The former world No1 posted a cryptic message on Twitter, saying: “My dear fans & supporters. Pls tune in to my Facebook page tomorrow at 6pm UK time, where I’ll be sharing something important with you live.”

There has been speculation in recent years about Ivanovic’s future in the sport, with the Serb struggling to replicate the form that secured her only grand slam title at the French Open in 2008.

The 29-year-old had a particularly tough 2016 season, winning 15 matches all year, the most recent in June, and slipping to 63rd in the rankings.

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After enduring a fifth successive defeat in the opening round of the US Open in August, Ivanovic insisted she was not thinking of retiring, saying: “I just need to really see why is this happening. I had struggles throughout my career. I had some tough times. This is not the first time I’m going through this. It just hurts because I know what I invested.”

A few days later Ivanovic, who married the Manchester United midfielder Bastian Schweinsteiger in the summer, announced she was ending her season early to allow wrist and toe injuries to fully heal.

But she vowed to return, saying: “I had to make this difficult decision so that I can fully recover and play injury-free next year. I can’t wait to play again and be back on court fully fit in 2017.”

Ivanovic posted pictures of herself back in training in November and was one of the highest-profile players to compete in this year’s International Premier Tennis League in Asia. She is due to begin the new season at the ASB Classic in Auckland, starting on 2 January, and is also on the entry list for the Australian Open.