Serena Williams spent nearly a year working with Wilson LABS on new stick.
Practice isn't confined to the Arthur Ashe Stadium court.
The Spanish star hopes to make a full recovery before the Open, but time is running out.
Australian Open champion Sofia Kenin will wear Fila's red, white and blue in New York.
American will play with the the SX 300 frame.
Wimbledon winner is sixth member of Top 10 to opt out of New York.
World No. 7 is heading for New York.
