15 women have achieved the feat, but only one has done it more than once.
Four of the world's Top 5 players are in the draw in Berlin, with Coco Gauff as the top seed.
The World No.1 and World No.2 will take to the grass next week.
Dr. Antoine Gerometta, who performed the arthroscopic surgery to repair Novak Djokovic's medial meniscus, on his Wimbledon hopes.
A list of the 29 players who have ascended to the top of the WTA rankings since 1975.
A list of all 29 payers who held the No.1 rankint
The Pole needs rest after running the table on clay this spring.