Veronika Kudermetova pulls ahead of Maria Sakkari this week, but there is much high-stakes tennis to be played.
The American leads the ranking charge this week after his title in Tokyo.
Jessica Pegula, Coco Gauff, Danielle Collins, Madison Keys and Taylor Townsend will represent the U.S. in Glasgow.
The Czech is the talk of the tennis world after an epic victory over No.1-ranked Swiatek in Ostrava.
The Serb has never been shy about his ambition, and he continues to dream as his title count hits 90.
Seven top-10 players, including Iga Swiatek, will take their place in next week's loaded San Diego draw.
The Russian said he felt he would be risking too much by continuing.