That is the prediction of Sky Sports pundit Peter Fleming.
Federer slumped to a straight-sets loss against Nishikori on Sunday – 7-6 (7-4), 6-3 and he looked a pale shadow of himself with more than 30 errors flying off his racket.
The world No 3 has struggled for form of late and hasn’t quite appeared the same since his shock loss to John Millman in the fourth round of the US Open in September.
And Fleming thinks Federer can only improve against Dominic Thiem, who lost his opening match in the round robin stage to Kevin Anderson.
“I think he will play better. The first match is always difficult in any event especially against a top player like Nishikori,” former American tennis player Fleming said.
“There’s no question Federer will play a lot better.
“He has to win.”
Fleming was baffled by Federer’s display against Nishikori, adding: “It was a real shock. It appeared in the first as if Federer had the upper hand.
“It seemed like a matter of time before Federer would get some balls in play and would run away with it.
“But Nishikori came up with a couple of unbelievable shots.
“He even said after the match they were a bit lucky.
“To fend Federer off and then in the tie-breaker, Nishikori played a good solid tie-breaker.
“Federer made a couple of unforced errors and then the errors cascaded.
“The world No 3 really struggled from that point on.
“He looked like a shell of a man in the second set.”