That’s the belief of Greg Rusedski.
The Swiss icon stormed past Denis Shapovalov in the semi finals with a stylish 6-2, 6-4 win against the 19-year-old Canadian.
Federer is now into his 50th Masters 1000 final – more than any other player on the ATP Tour has managed with Rafael Nadal having made 49.
The 37-year-old will hope to claim title No 101 of his career after securing a century of tournament triumphs in Dubai recently, having also lost in the final of the Indian Wells Masters since then.
But Federer has been told he must work on his serve, having kept just 47 per-cent of his first serves in against Shapovalov – who noticeably struggled with nerves in coming up against his childhood hero.
Previewing Federer’s clash with big-hitting Isner, Rusedski told Amazon Prime: “Definitely [that number has to come up]. No question about that.
“That will have to be better because Isner’s not going to be intimidated. He knows Roger, he’s been around with him for 15 years.
“He knows the guy, he’s beaten him before. So why not? As he said, ‘I’m not winning this tournament every week.’
“He’s going to say: ‘All the pressure’s on Federer.’ He’s got that to have an advantage against Roger.
“Isner, if he can serve those corners, it doesn’t matter if it’s Roger stood there. That’s the thing.
“What I liked from Isner [in his semi-final win over Felix Auger Aliassime], he went away from a few of his patterns to win that match, he played a very, very smart match.
“It’s going to be interesting to see where the crowd’s at. He’s American, everybody loves Federer around here.
“I think he’s got a shot there because as Roger alluded to, ‘I like playing big servers but nobody likes it when it’s working.’”
Previewing their clash, Federer said: “I know what to expect, that he will not miss many serves. He’s got an amazing serve, one of the best in the game forever.
“It’s really hard to play against him. I saved match point the last time I played against him at the Laver Cup, that was tough.
“Big fan of his. I actually really enjoy watching him play. I know some guys don’t but I love it. I honestly love big servers.
“To watch them and see if they’re going to ace every second or third point. For me that’s exciting.
“It’s like a penalty shootout in soccer, it’s just in tennis. I quite enjoy it.
“For me I’ll be the goalie, I’ll try my very best. I’ll try to get as many balls back as possible and I hope we’ll play a good match.
“I’m excited to play John because he had a really tough match against Felix [Auger Aliassime] today, that was an awesome performance from him.”
The 2019 Miami Open final will get underway at approximately 6pm UK time.