Big night with our two 🇺🇸SF women's matches! Who gets your vote for the #EmiratesAce of the Day - @Madison_Keys or @sloanestephens? Tag your favorite in the comments below and include #EmiratesAce for a chance to win tickets & other prizes! #USOpen #arthurashestadium #usopen2017 #aces #madisonkeys #sloanestephens #tennis