South Korea face Saudi Arabia in a friendly at Newcastle United's St James' Park on Tuesday with Jurgen Klinsmann under severe pressure after a wretched start as coach.

The German legend was only appointed in February but his South Korea side have failed to win in the five games since, losing twice and drawing three times.

The latest disappointment was a drab 0-0 stalemate away at an equally off-colour Wales last week, after which skipper Son Heung-min came to the defence of 59-year-old Klinsmann.

"I understand where fans come from, as someone who's been on the national team for a long time," the Tottenham Hotspur forward told reporters in Cardiff.

"I am not saying the coach is always right, but I also don't think fans are always right either."

South Korea reached the last 16 of the Qatar World Cup before being outclassed 4-1 by Brazil, after which coach Paulo Bento said he would not carry on.

The Korea Football Association launched a protracted search for his successor before settling on Klinsmann, a World Cup winner as a player but whose coaching career has never hit the same heights.

Many South Korean fans were underwhelmed by the appointment and performances since have only added to those misgivings.

Klinsmann, whose previous coaching job was a short stint with Hertha Berlin more than three years ago, started with a 2-2 home draw with Colombia, before home defeats to Uruguay and Peru.

Then came a 1-1 home draw with El Salvador and the goalless stalemate with Wales, the result and listless nature of the performance piling the pressure on former United States coach Klinsmann.

Despite boasting Asia's finest attacker in the talisman Son, South Korea conjured up just one shot on target against the 35th-ranked Welsh.

South Korea have scored four times in five matches under Klinsmann, who was a prolific striker as a player in his pomp.

But it is what the former Germany skipper and coach is doing off the pitch that has equally angered fans.

South Korean supporters and media accuse him of reneging on a pledge to move to the country, saying he spends more time at home in California than he does in South Korea.

Klinsmann's media duties away from the South Korea job have also been touted by critics as more evidence that he is not sufficiently committed to the job.

Choi Dong-ho, a commentator and director of the Center for Sports Culture research group, said Klinsmann appeared "negligent".

"Considering his limited familiarity with Korean players, he should at least be watching all K League games in person rather than being 'briefed' by other coaches while he stays abroad," said Choi.

Failure to beat Saudi Arabia, who are ranked 54th in the world to South Korea's 28, would leave Klinsmann clinging to his job after less than seven months in charge.

"Klinsmann's seeming lack of urgency in light of poor performances hasn't sat well with South Korean fans, many of whom have already begun calling for the German tactician's head," Yonhap news agency said on Monday.

Klinsmann insists that the team is in transition and his focus is on the Asian Cup, which takes place in Qatar in January-February.

"How prepared are they mentally for a big tournament? Can they deal with all the pressure, all the expectations and all those different elements?" Klinsmann said after the Wales draw.

"It's a growing process," he added.

"And I'm pleased overall with what the players showed, and we'll keep growing game by game."