Home favourite Kei Nishikori has advanced through to the quarter-finals of the Japan Open with a straight-sets victory over Sam Querrey.

The world number six, who is seeded second in Tokyo, needed just an hour and a quarter to beat his American opponent.

The first set was an extremely close contest, with neither man offering his opponent a single break point so a tie-break was needed.

Querrey broke Nishikori's serve on the first point, but then the Japanese reeled off five points in a row before claiming the breaker 7-3.

Nishikori had the momentum and although he failed to convert the first break point of the contest in the opening game of the second set, he soon struck to break the American's serve to lead 3-1.

Another break in the ninth game saw him seal a 6-3 success to book his place in the last eight.

The defending champion will face either sixth-seed Marin Cilic or another American, Steve Johnson, in the quarters.