Swiss great Federer made clear in a press conference on Thursday (AEST) that the tie-up with Nadal was the one he wanted for his finale.
That made it practically inevitable they would be paired together, and it was confirmed that Federer and Nadal would join forces for Team Europe, to take on Team World's Frances Tiafoe and Jack Sock.
"I think it could be quite a unique situation if it were to happen, for as long as we battled together, to having always this respect for one another, the families, our coaching teams," Federer had said ahead of the announcement. "We always got along really well.
"For us as well to go through a career that we both have had and to come out on the other side and being able to have a nice relationship, I think is maybe a great message as well, to not just tennis but sports and maybe even beyond. For that reason I think it would be great."
By the time Nadal emerged as a teenage prodigy, Federer was already a grand slam champion, and their rivalry will go down as one of the greatest in tennis history.
They have met in nine grand slam finals, with Nadal winning six of those on his way to a career 24-16 winning record against Federer.
Federer, 41, is retiring after deciding the knee trouble that has plagued him in recent years will not allow him to extend his career any further. He will sign off with 20 slam singles titles, two behind Nadal, who has won the most of all men.
Federer is playing just one match at the Laver Cup, the tournament he was involved in setting up, with his big send-off coming in London, where he won eight Wimbledon titles.
This weekend's tournament is being staged at the O2 indoor venue, where Federer has previously twice won the ATP Finals.
He said of his farewell to tennis: "I'm happy to do it here in London. This city has been special to me. Maybe the most special place with Wimbledon down the road and here at the O2.
"[Having] played here and qualified for so many years and won here as well. I just thought it was very fitting."