Juan Martin Del Potro of Argentina celebrates after defeating Milos Raonic of Canada during their men's singles final match at the Japan Open tennis championships in Tokyo October 6, 2013.[Photo/Agencies]

TOKYO - Top seed Juan Martin del Potro beat Milos Raonic 7-6 (7-5) 7-5 to win the Japan Open on Sunday and secured his third title win this season at the Ariake Tennis Forest Park in Tokyo.

Del Porto, who was filling in for an injured Andy Murray, managed to save three break points in an evenly-contested first set, but settled the matter with a stunning ace -- the fourth of the set -- to lead 7-6 (7-5).

Del Porto, faced an obstinate, big-serving Raonic, who smashed no less than 17 aces home and had his serve broken just once in the second set. That was enough however for Del Porto to take the match with a stunning forehand pass and deny the Canadian his 42nd match win of the season and his ninth straight win in Asia.

The title, following victories in both Rotterdam and Washington, sees Argentina's Del Porto, ranked seventh in the world, take his championship tally up to three this season.

Del Porto said he was lucky to be invited to play in the tournament that he reached the finals of in 2008, only to lose to Tomas Berdych.

"I was delighted to be invited to play this year and as a wild card it was the only way for me to play," Del Porto said.

"I had to stay focused in the match and take my chances when they came. Milos served really well, but thankfully I broke his serve in the second to last game," he said.

Raonic, who is still in contention along with del Porto to qualify for the season-ending ATP World Tour Finals in London next month, said that moving up in the rankings is important, but his improvement as a player is what pleased him most.

"Rankings is just icing on the cake, for me the most important thing is improving as a player. If you keep getting better your ranking will improved," he said, adding that he was preparing well for games and had a good training regimen that has been helping his physical and mental condition on court.