The big-serving Canadian blasted 34 aces past his bewildered Japanese opponent, including one that was timed at 231km/h (143.6 mph), to come from behind and win their semi-final 6-7(4) 7-6(4) 7-6(4).

"We spent a lot of time of practising, there's a lot of cold days in Canada," Raonic told a courtside interviewer when asked the secret to his success.

Raonic will face either Roger Federer or Grigor Dimitrov in Sunday's final of the Australian Open warm-up tournament at the Pat Rafter Arena.

Ranked eighth in the world, Raonic is emerging as one of the favourites to win the first grand slam of 2015 after he announced his arrival by reaching the semi-finals of Wimbledon last year.

And the 24-year-old has started the new season where he left off, reaching his 14th career ATP final and avenging his loss to Nishikori in last year's Japan Open final.

Raonic brought his heavy artillery to the Pat Rafter Arena, holding each of his 18 service games and committing just three double faults in the two-and-a-half hour clash.

One small error cost him the first set. After the first eight points in the tiebreaker all went with serve, Raonic handed Nishikori a mini-break when he dumped a backhand into the net.

That was all Nishikori, also a rising star of the game, needed to take the opening set in 49 minutes, with the U.S. Open finalist winning the next two points on his own serve, sealed with a backhand winner.

Raonic, serving at an average of almost 30km/h (18 mph) faster than Nishikori, continued his blitz in the second set and the pressure eventually told when Nishikori double-faulted in the tiebreaker, allowing the 25-year-old Canadian to level the match.

The third set also went to a tiebreaker as neither player was able to break each other's serve in a high-quality contest.

Nishikori handed Raonic the advantage when he sprayed a forehand volley wide then the Canadian sealed his win with a devastating return winner.

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