Under-fire coach Jurgen Klinsmann said he "has to be positive" ahead of South Korea's Asian Cup showdown with Saudi Arabia on Tuesday after stuttering into the last 16.

The Koreans conceded six goals in the first round and drew with Jordan and 130th-ranked Malaysia to finish runners-up in their group.

Klinsmann and his players have faced fierce criticism back home, with the German legend being mocked for telling reporters to book their hotels in Qatar until February 10 -- the day of the final.

"A coach has to be positive, a coach has to believe in his team and make it happen," the 59-year-old Klinsmann, a World Cup winner as a player, said on Monday.

"If the other team is better and beats you, then you can still go back to the hotel and cancel."

South Korea finished behind Bahrain in Group E after conceding a 105th-minute equaliser in a 3-3 draw with Malaysia.

Klinsmann was pilloried for smiling on the bench after Malaysia scored but insisted it was "because I saw it (the goal) coming".

He was more interested in talking about Saudi Arabia and said he could see Roberto Mancini's "handwriting" on the team, five months after the Italian took over.

The winner of the last-16 tie faces Australia in the quarter-finals.

"We have the belief that we can beat Saudi Arabia but it will be a lot of work," said Klinsmann.

"It will be a nail-biter. It might go into a penalty shoot-out."

Saudi Arabia won Group F but came from a goal down to beat Oman 2-1 with an injury-time winner in their opening game.

They also struggled in front of goal in a 2-0 victory over a Kyrgyzstan side that played almost half the game with nine men.

They rounded off their group with a 0-0 draw with Thailand.

Mancini shrugged off his team's lack of bite in front of goal and said they could profit from South Korea's defensive woes.

"If they conceded six goals in the group stage it doesn't change their strength because they have very good players and they score a lot of goals," he said.

"We know that if we attack we can have a chance to score," he added.

Saudi Arabia have only conceded one goal so far at the tournament and Mancini said they had "improved a lot" since he took over in August.

But he is wary of South Korea's attacking threat, led by skipper Son Heung-min, and urged his side to "play as a team".

"It is not only their attackers -- all their team is very good," he said.

"Most of their players play in Europe and have a lot of experience."