The 56-year-old coach was speaking in the aftermath of Nadal's triumph at Flushing Meadows to pick up his 16th men's singles Grand Slam title after beating Kevin Anderson in straight sets.
It was the 31-year-old's second major title of the year and he could have been closer had he beaten Federer when the two met in the finals of the Australian Open at the start of the year. Nadal's coach, however, is not concerned as he remains confident that the record is within reach as he foresees his nephew winning some more Roland Garros titles to add to his ten thus far.
Nadal had not won a tournament on hard courts since 2014 and finally triumphed at the US Open in the 35th time of asking. His win cemented his place as the world number one and is favourite to end the season for the fifth time as the men's singles' top-ranked player. Federer, the current world number two, however, does have a chance to fight for that honour going into the latter part of the season.
"We will get to Federer's 19, yes," Toni Nadal said, as quoted by the Metro. "I think it will happen. It's difficult, but there is some more Roland Garros and I am confident other titles will come."
"When he was 12, 13 or 14, you never think he will get to this level. I am very happy to see my nephew lift so many trophies, knowing that he has achieved another piece of history.
"He has won a hard-court tournament for the first time since 2014. We are very happy that he has won another Grand Slam, his 16th, and is in a position to fight for No. 1," he added.
"It was unimaginable that would happen, of course. But I had faith that Rafael would win one more Grand Slam, I tell you truthfully," the world number one's longtime coach admitted.