Another World Cup game saw another clean sheet for miserly Switzerland and coach Kobi Kuhn could not have been happier after his side's 2-0 win over 2002 semi-finalists South Korea earned them a place in the knockout stages.

A goal in each half from Philippe Senderos and Alexander Frei maintained Switzerland's unbeaten run at the tournament and saw them finish on top of Group G ahead of 1998 world champions France.

But while the goals have started to come for Kuhn's team, the defence remained unbeaten for the third straight game, meaning Switzerland are now the only team in Germany yet to concede a goal.

"There were a couple of dangerous situations where we were lucky," said Kuhn after the Swiss booked a second-round tie with Ukraine.

"But in all the games so far we didn't just do a good job up front but at the back too.

"No goals have been scored against us and I would like to congratulate our defence for their great performance.

"For the Swiss side to get seven points, with four goals scored and zero against, I think that's great."

Needing only a draw to qualify for the last 16, the Swiss rarely looked in danger of achieving anything less as the Koreans pushed for the victory they needed to progress.

Senderos gave Switzerland the lead with a header following Hakan Yakin's free-kick into the penalty area midway through the first half and Frei doubled the advantage 13 minutes from time with the Korean defence expecting referee Horacio Elizonda to blow for offside.

But the Argentinian official allowed play to continue and Frei rounded goalkeeper Lee Woon Jae to score.

"It was a very, very intense match," said Kuhn.

"We knew beforehand that the game against the South Koreans would be tough.

"They are a very fit team and they are very strong, and we prepared our team very well for our opponents.

"We adapted well and didn't have to run as far as they did. We were the smarter team. Despite being young, the players have experience and they used that to fight back."

South Korea coach Dick Advocaat was left to rue Elizonda's decision-making as the referee also refused to give the Dutchman's side a penalty early in the second half after Patrick Mueller looked to have handled the ball.

"Most of the decisions were not on our side," said the former Netherlands manager. "Sometimes luck is with you and tonight it wasn't.

"We didn't get the handball but that's going to happen in a game. Switzerland deserved to win, not because of the second half but because of how they played in the first half."