Bernard Tomic gave his Australian Open hopes a major boost by downing Japan's Kei Nishikori 6-3 1-6 6-3 in the quarter-finals of the Brisbane International.

Combined with the withdrawal of Frenchman Richard Gasquet (No.9) from the first grand slam of the year, the victory ensured the Aussie - ranked No.18 at the start of the week - would move above Feliciano Lopez (17) after the Spaniard was beaten in the first round of this week's Qatar Open.

That will guarantee Tomic a top-16 seeding in Melbourne for the first time in his career, meaning he would avoid a match up with world No.1 Novak Djokovic until at least the fourth round.

The Queenslander will meet Milos Raonic in today's semi-finals, the Canadian emerging victorious in their only clash in Tokyo two years ago.

Tomic had never taken a set off Nishikori, losing to the world No.8 6-0 6-4 at the same stage of the tournament in Brisbane 12 months ago.

This time it was his serve that proved the difference, sending down 14 aces and winning 73% of his first serve points.

"This is very, very special for me," Tomic said after the match. "Looking back last year I was well beaten by Kei, but today I played very different. I've improved so much since last year."

Raonic booked his place in the semi-finals with a 6-4 6-4 win over France's Lucas Pouille. The No.4 seed won a staggering 93% of his first service points in the opening set.