Serena Williams poses with Chloe Blacker during the Delta Challenge.

In this handout image provided by Delta Air Lines, Serena Williams poses with Chloe Blacker, the fastest female server during the Delta Challenge. 

A special pop up court was created by Delta where people could test the speed of their tennis serve and receive coaching tips during a masterclass from Serena Williams.
June 2014 in London, England.