Nishikori heading for Tomic clash

Former US Open finalist Kei Nishikori has marched into a possible Brisbane International quarter-final match against Australia's Bernard Tomic.

The Japanese star extended his career record against Kazakhstan's Mikhail Kukushkin to 4-0 with a professional 6-3 6-4 victory on Pat Rafter Arena.

Victory means the second seed will meet the winner of Wednesday night's clash between seventh seed Tomic and Czech veteran Radek Stepanek.

Nishikori, a two-time Australian Open quarter-finalist, will be aiming to go at least one step further than his past three visits to Brisbane, which have all ended in semi-final defeat.

Austria's Dominic Thiem is also through to the last eight, continuing his good form with a comprehensive 6-3 6-2 win over American Denis Kudla.

The youngest man in the world top 20, 22-year-old Thiem backed up from his three-set win over Australia's James Duckworth on Tuesday with the 57-minute demolition of world No.69 Kudla.

Thiem next faces third seed Marin Cilic after the 2014 US Open champion beat Korean Hyeon Chung 7-5 7-6 (7-3).