Big night with our two SF women's matches! Who gets your vote for the #EmiratesAce of the Day - @SerenaWilliams or @naomiosakatennis? Tag your favorite in the comments below and include #EmiratesAce for a chance to win tickets to the Women’s Finals day on Saturday! #USOpen #arthurashestadium #usopen2017 #aces #serenawilliams #naomiosaka #tennis