Gauff's upset over Osaka highlights changing of the guard

The 15-year-old's victory over the defending champion capped a night of surprises (Serena's exit) and goodbyes (Caroline Wozniack's career finale).

source http://www.espn.com/tennis/story/_/id/28552468/coco-gauff-upset-naomi-osaka-highlights-changing-guard-women-tennis