Rather than trying to mimic the powerful style of play that Williams used to revolutionise women's tennis and collect 23 Grand Slam titles, 17-year-old McNally instead prefers to model her game after Swiss great Federer.
"The big things are the way he carries himself on court. I think that's huge," McNally said after her 5-7 6-3 6-1 second-round loss to Williams on Wednesday.
"I try to do the exact same thing.
Also the way he plays, he serves and volleys, looks to get to the net. He takes a lot of time away from his opponents.
"I really like the way he plays, mixes in the slice, the dropshot, volleys really well.
There's so many things I like from his game.
Hopefully I can keep working on those and become just like him."
The American wildcard did her best impression of the 20-times Grand Slam winner in her second-round clash with Williams as she relied on a serve-and-volley approach and lethal slice backhand that did well to unsettle Williams for long stretches.
While McNally, who was not broken until the sixth game of the second set when she fell behind 4-2, ran out of steam in her bid to derail the six-times champion, she still managed to impress world number eight Williams.
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"It was definitely something to get used to," Williams said of McNally's playing style. "You don't play players like her that have such full games.
"She just overall played really well."
McNally, competing in only her sixth tour-level event of her career and against the highest-ranked player she has ever faced, showed she was anything but starstruck as she took the court under the lights inside Arthur Ashe Stadium.
Instead, McNally played the match of her life on the biggest stage in tennis and against one of the greatest to ever play the game and it was shots from Swiss great Federer's repertoire that gave her a fighting chance.
"I didn't think who was on the other side of the net as much.
But obviously I knew I was playing against the greatest of all time. I knew that I had to bring a certain level," said McNally.
"I walked out there and I had the chills.
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That was the most insane atmosphere.
I've never played on a court nowhere near that big, especially a night match. I couldn't have asked for anything better.
"It was just an unbelievable experience, something that I'll never forget for the rest of my life."
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