Carlos seem to thrive at big events and soon the big three will be gone for good.Iga is good for now who knows with women tennis,there could be a young player that would blow everyone away in the coming years.I think Krejickova is a player that can stop Iga,the way she played her in Czech Republic showed if one stays with Iga,it's doable.At present Iga has no player to rival her, her game suits all surfaces, if she stays healthy, does not over play I will pick Iga.