Paraguay advanced into the World Cup quarterfinals for the first time as they beat Japan on penalties after a goalless 120 minutes on Tuesday.

Oscar Cardozo slotted home the winning kick after Yuichi Komano had smashed his effort against the bar in the first shootout of the 2010 tournament.

Japan, bidding to become the first Asian team to beat a South American side in the World Cup history, threatened Paraguay 25 seconds into action as Yoshito Okubo connected a wayward pass in the Paraguay midfield and blasted a low shot from 25 meters which went wide one meter of Justo Villar's goal.

Paraguay keeper sweated at the third minute as he pulled off a save of a low shot of Komano, who raced down the right and fired straight at the target.

The first 10 minutes saw Paraguay had most of the ball in their own half, but when they got within 50 meters of the Japanese area, they were surrounded by blue shirts.

At the 19th minute, Lucas Barrios beat three Japanese defenders to fire from close range and Yoshikatsu Kawaguchi knocked out the ball with his right knee. The Japanese replied with Daisuke Matsui's long volley which rattled the Paraguay bar.

At the 28th minute, Paraguay's Claudio Morel swung in a corner to cause a goalmouth melee in which Roque Santa Cruz fired wide.

Moments later, Marcus Tulio Tanaka saw his goalwards shot saved by Villar.

At the 39th minute, Japanese Daisuke Matsui sprinted down the right and crossed to Keisuke Honda, whose spinning shot went just a meter off the post.

Six minutes after the restart, Nestor Ortigoza broke into the Japanese area with dazzling moves but he took too long to deliver his shot and was tackled by Tanaka.

Edgar Benitez wasted another chance as he showed off his dribbling skills at the edge of the area, instead of taking a quick shot.

Paraguay continued to press hard as Cristian Riveros forced a save from Kawaguchi.

Neither side were able to break the deadlock in the rest of full time.

The Japanese keeper was brilliant in extra time, saving Barrios' glancing header and blocking his point-blank shot two minutes later.

A few minutes later Japanese set-piece specialist Keisuke Honda curled in a free kick from the left and though it was a meter wide of the far post, Villar pushed it out to make sure.

Paraguay will take on the winners of Spain-Portugal game for a semifinal berth.

Paraguay coach Gerardo Martino said the game decided by penalties was not fair.

"I know it's unfair to decide the match by penalty shoot-out but that's the way it is," he said.

Japan coach Takeshi Okada claimed his side didn't have regrets.

"I am proud of my players who also played for Asia until the end," he said.