Three months later, she reached the final of the French Open, where she lost to current world No.1 Halep.
In such circumstances some players might have ended their season early, but Halep said she had been determined to push herself to the limit.
'I'm doing physio to try to make (my back) stronger, but I haven't practised 100 percent yet, ' Halep added.
"I'm honoured to qualify for my first WTA Finals", said Stephens in a media release.
The Kremlin Cup runs this week and the WTA Finals, which is for the top eight players in the world, begin in Singapore on October 21. "I'm looking forward to meeting the fantastic fans in Singapore, exploring the city, and competing against the best players of the season".
"Finishing the season as the world No. 1 a year ago was a huge honour for me", Halep said in a WTA news release.
She is particularly keen to do so because the year-ending WTA Finals in Singapore start in six days' time. "So I don't know now, but for sure I will take a decision for my health first". "I give everything I have the first part of the year and then it's hard for me to play", said Halep, who also reached French Open finals in 2014 and 2017 but lost both times. It is noteworthy that six other players that are ahead of Svitolina, already qualified for the Final tournament in Singapore.
Dealing with a herniated disc, Halep is in Moscow this week to test out her back and get some match prep before Singapore.