During day two of the #USOpen we saw incredible #Aces by @carowozniacki, @rogerfederer & @petra.kvitova! Who has your vote for the #emiratesAce of the day? Comment your pick below! _ #USOpen50 #builtforglory #tennis #nyc #tennis #emirates #RogerFederer #CarolineWozniacki #PetraKvitova