German tennis star Julia Goerges has announced her retirement after a 15-year professional career. 

The 31 year-old, who is a 2018 Wimbledon semi-finalist, revealed the news in an open letter.

The star has retired ranked world No 45, but reached a career high ranking of No 9 in 2018. 

She wrote: "I am writing to you, because I am ready to say “Goodbye”. When I started playing tennis at the age of 5, I would never have thought that we would go such a long way together.

"You have given me so many different types of emotions throughout our journey and I am very thankful for everything you have shown and taught me. I learnt how to deal with the toughest losses but also enjoy the most amazing wins of my career, to fight back many times when I was struggling with you and through it all we never lost sight of our dreams.

“I always knew how I would feel when it is time to say goodbye to you, and that moment has arrived. I am ready to close the tennis chapter of my life and open a new one, which I am really excited about.”

Goerges made her professional debut on on the ITF Circuit in Germany in 2005 and went on to win 12 WTA titles including the Elite Trophy in 2017.

She was also a two-time semi-finalist in the doubles at the Australian Open and reached the mixed doubles finals at the 2014 French Open with Nenad Zimonjić.

Two-time Grand Slam winner Simona Halep said she was ‘sad’ she won’t be seeing Goerges on tour.

 She wrote: “Ohhh, this is such happy and sad news. I’m sad that I won’t see you on tour any more and happy because it means you are happy off court and you are ready to start another chapter! Your future looks very bright so I’m wishing you all the best and will keep in touch!”

Tunisian star Ons Jabeur said: “Julia you will be missed. Congrats on an amazing career.”

Agnieszka Radwańska, who won 20 WTA titles, wrote: “Congratulations on a great career Julia! Wish you the best in retirement.”

Former world No 1 Karolína Plíšková said: “My dear @juliagoerges , I just heard the news and wanted to dedicate you a few lines. First of all, congratulation on your fantastic career! We have experienced a lot of fun on and off the court, and I feel privileged that I had a chance to meet you!”

“Even though we achieved so many good results, our friendship is what I cherish the most! Thank you for all the lifetime memories, and I wish you all the best in the next chapter of your life! Happy retirement @juliagoerges”

Two-time Wimbledon champion Petra Kvitova added: "Jule! Wishing you all the best for your life away from tennis. Thank you for your big smile and for our battles on the court. We will miss you.”