Re: Who will end the 2019 streak of no repeating winners?
I can see either Petra or Kiki ending it in Stuttgart. They both like clay and Petra obviously prefers indoor conditions. Petra has also nearly ended the streak already in both Dubai and at the Australian Open.
Having said all that, Svitolina also likes clay, is back after some time off, and has usually won a Premier or seven by this time of the year. So I can see her taking the title and the streak continuing after Stuttgart.
I dunno about Yastremska in Istanbul. She's been messy all year, and there are a few strong players and a few clay lovers in the draw (CSN, Giorgi, Sakkari, Martic, Strycova, Buzarnescu, Tomljanovic, Jabeur, Maria, Flipkens, Mladenovic).