That is the view of former British No 1 John Lloyd.
Cilic faces 19-time Grand Slam champion Federer in the Australian Open today.
The Croat boasts just one Grand Slam himself and his record against Federer reads W1 L8.
Federer is the favourite to claim the title he won last year when beating Rafael Nadal in the final.
The Swiss is yet to lose a set all tournament.
And Lloyd reckons Cilic will struggle unless he hits the very top of his game.
Asked on BBC 5 Live if Cilic can claim victory, Lloyd said: “There’s a chance but it’s a small one.
“Cilic has to play at his best and Federer has to play less than his best.
“I will go with Federer. But it’s going to be a great final.”