Team World captain John McEnroe fumed after Nick Kyrgios was forced to pull out of his match with Dominic Thiem with injury.
Kyrgios was due to face Rafael Nadal in the second match of the day but the Spaniard pulled out with a hand injury.
But following the first match which saw John Isner and Jack Sock beat Roger Federer and Stefanos Tsitsipas, McEnroe announced Kyrgios will not be able to play.
He said: “Unfortunately Nick is not ready to go. We are going to be going into conference. Stay tuned.”
It was then confirmed that Thiem would, in fact, face Taylor Fritz.
McEnroe was then asked to explain what was going on and his dissatisfaction was clear.
He said: “Nick’s shoulder has been bugging him. He was talking about it last night. I don’t know what to tell you other than we wanted him to come out 100 per cent and he didn’t feel like he could. So that means we’ve got to put somebody else in.
“We were told on the way over that Rafa couldn’t play. Well that means you can’t play the same guy and that sort of limited our options. I thought Denis was playing well and Taylor played well also. But we were looking to maybe put Denis in.
“I’ve always been maybe not a stickler for rules. The last day, we are supposed to be matching up the way we want to and it ends up being the total opposite. That’s too bad. Coming from someone who never bent any rules, it seems like a little bending is happening.
“That would be the way I see it from my perspective.
“Let’s say for the sake of argument Rafa came out this morning and couldn’t do it they have got to be able to adjust the rules and make it so that the guys that should be benefitting, have the option of matching up can do so after the fact.”
Broadcaster Mark Petchey would later say: “I get a sense that there’s been a lot going on behind the scenes.
“And that’s not a happy looking Roger Federer. Of course, he lost his doubles which is probably the reason why.
“But just the way things have unfolded in the last 25 minutes haven’t been conducive to the atmosphere.
“Obviously it will pick back up when he comes back on court. But I get a sense between the two teams now that there’s a fair bit of angst about what has unfolded.”