AUCKLAND: Top seed Juan Martin Del Potro maintained his meteoric rise up the tennis world rankings with a 6-4, 6-4 win over American Sam Querrey in the final of the Heineken Open here Saturday.

The Argentine world number nine has risen 56 places in the rankings since the middle of last year and carried the momentum into 2009 by clearly outclassing the tournament's sixth seed.

In July last year the 20-year-old won his first ATP title in Stuttgart, quickly followed by more victories in Kitzbuhel, Los Angeles and Washington, as well as being the beaten finalist in Tokyo.

He proved in Auckland -- a warm-up for next week's Australian Open -- that he has lost nothing since last year, dropping only one set all week.

Querrey said his loss was largely down to being able to successfully land only 55 percent of his first serves.

Del Potro controlled most of the rallies, with Querrey relying largely on his booming first serve and ground shots to keep him in the match.

Querrey served two aces at deuce to go 4-3 ahead in the first set after both players had dropped a serve each.

But Del Potro, playing with greater steadiness than the world number 36, broke back in the ninth game and went on to hold his serve and secure the first set.

In the fourth game of the second set, underdog Querrey had the chance to grab the first service break.

But Del Potro again showed the ability to lift his game when needed, fighting back to blast two aces on the game's third deuce to draw level at 2-2.

Del Potro grabbed the initiative in the ninth game, pushing his opponent around the court with precision to take a 5-4 lead, before holding serve to secure the title.