Cilic will take on Blake in the first reverse singles on Sunday, and Karlovic is scheduled to face Fish in the final singles, the U.S. needing to sweep the day to advance to the semifinals against either Argentina or the Czech Republic.

“It’s always interesting with them around, I’ll tell you that,” McEnroe said, to laughter from the press corp. “Where they are, hilarity ensues most times, in a good way. I get a kick out of watching them practice. Even when they’re on the practice court, they start fighting with each other, I just think it’s hilarious. They always add a certain dynamic to the matches. On top of that, they’re the No. 1 team in the world. That’s always something that you want to have on your side.”