Play of the day imo.
Bertens is in excellent form, winning 16 in a row (Nurnberg/RG single/double), confidence is through the roof. Against Giorgi she played at a very high level in the first set, making slim to nil mistakes. The match against Kasatkina was a tough one but she showed some mental toughness coming out as winner in 3 (10-8 last set). The after that long match she beat the Williams sisters in the doubles.
I just watched an interview with her coach Sluiter and he was very well aware of the fact that Kiki's fatigue is a thing to keep in mind, but like he said: "There is no better way to prepare for a match after a long battle than beating the Williams sisters'. I agree.
Although I don't think Bertens will come out on top against Keys (though @ 2.6/2.7 is some decent value), I believe she will be able to compete with Madison for some serious time and take a set from her. Keys is a hard hitter and in a good form herself as well, but atm everything is coming Bertens way, it might end today but atleast she will give up a fight and take this to the wire.
What are your angles on this?
GL!