Having landed in the same half of the U.S. Open draw when it was revealed last week, Rafael Nadal and Roger Federer were never that far away from their long-overdue and first-ever head-to-head encounter at this tournament.

And then the first two rounds happened.

Nadal started off slowly against Dusan Lajovic but eventually recovered for a straight-set victory after breaking serve to stay alive in the first set at 4-5. The world No. 1 started even slower against Taro Daniel on Thursdaynight, trailing by a set and a break only to storm back and win in four.

If that was cause for concern, Federer’s first two matches inspired downright panic. The 36-year-old needed five sets to hold off Frances Tiafoe, even failing to serve it out at 5-3 in the fifth before breaking for the win. Federer made an even bigger mess of things against Mikhail Youzhny, falling behind two sets to one before surviving another five-setter. All the while, his back looked far less than 100 percent.

But then the third round happened.

Although Nadal got off to another disastrous start on Saturday afternoon (trailed by a set and faced double break point early in the second), he raised his level considerably to overcome Leonardo Mayer 6-7(3), 6-3, 6-1, 6-4. The top-seeded Spaniard finished with 39 winners and 26 unforced errors, and in the last three sets he fired 30 winners compared to only 13 errors.

“I was able to play more free, to start to attack better with my forehand” Nadal explained after converting his first break of the match on his 14th chance midway through the second set. “I changed more forehands down the line, hitting some good backhands later. I think the level of tennis after that break have been very positive. I hope that last three sets can be a good turning point for me because, in my opinion, I played much better today than the two previous days later in the match. You need matches like this.”

Federer needed a match his Saturday night tilt with Feliciano Lopez, which started two hours late due to the length of Nadal vs. Mayer and a pair of three-set women’s matches that preceded it.

Erasing all back-injury fears, Federer improved to 13-0 lifetime against Lopez by crushing the 35-year-old 6-3, 6-3, 7-5. The five-time U.S. Open champion struck 13 aces while double-faulting only once and he doubled his unforced error count with winners (32 to 16).

“I was happy I had good energy because I think that was my biggest worry, that somehow after the two five-setters that I had, I was going to feel a little slow,” Federer noted. “It didn’t happen.”

And now it looks like Nadal vs. Federer will.