Tennis doubles champs furious, humiliated as overhaul brings in singles players and prize jumps to $1 million from $200,000

Grand Slam singles champions such as Jannik Sinner, Carlos Alcaraz, Iga Swiatek and Madison Keys will be playing for a little extra money — OK, a lot of extra money, by any standard: $1 million to the winning duo — and trying to get their hands on a trophy in the U.S. Open’s overhauled mixed…