Raonic, who upset Roger Federer in the 2016 final, is top seed this week but there's no outright favourite according to Nishikori and Austrian world No.8 Dominic Thiem, who both strongly felt it was an open tournament. "There's too many top players here," third seed Nishikori said.
In fact, Canadian Raonic is likely to meet main drawcard Nadal, flying in late from Abu Dhabi, in what looms as a good quarter-final clash.
With the depth of quality in the field, Thiem rated it among the strongest ATP250 tournaments of the year and also pointed to the lack of a form gauge.
Tomic will lead a charge of three Australians at Pat Rafter Arena and can set up an all-Aussie second-round clash with wildcard Jordan Thompson, who has drawn Swede Elias Ymer in round one.
World No.9 Nadal, in his maiden Brisbane appearance, has a tricky opening encounter against popular Ukrainian Alexandr Dolgopolov while second seed Stan Wawrinka will meet either Victor Troiki or a qualifier in the second round.
- AAP