Germany captain Michael Ballack said his side had to overcome their nerves to beat Austria and book a last-eight tie with Portugal at Euro 2008.

Ballack's thunderbolt from a free-kick proved enough for the Germans, who should have taken the lead early in the match through striker Mario Gomez.

"We were a little bit nervous in front of the goal and maybe that's why Gomez missed," said the Chelsea midfielder.

"We might have missed that chance but we fought to the end."

Ballack added: "It was a good free-kick. I hit the ball very well and it was important to score early in the second half."

Looking ahead to the quarter-final, Ballack believes Germany will face a tough challenge against Portugal.

"I think they've played very well so far. I expect a big game - they are one of the favourites.

"It's a big, big game for us but we can relax now three days."

Coach Joachim Low said he was delighted with the victory.

"I'm pleased to garner this important win in a match where we were under enormous pressure," he said.

"We knocked the host country out of the tournament, have advanced to the next round and got six points.

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"We are pleased that we showed that we belong in the quarter-finals even if we haven't played as convincingly as we would have liked to.

"I am sure, though, that the team will now get the lift we need, and that we can play competitively against Portugal."

Along with Austria's Josef Hickersberger, Low was sent to the stands late in the first half, after both coaches had argued with the fourth official.

"I told the referee's assistant we wanted to quietly get on with our coaching work in our zone and that's why we were both sent to the stand," said Low.