Sven-Goran Eriksson said he believes England can win Euro 2004 if they play as well as they did in beating Croatia 4-2 to reach the quarter-finals.
"If we play as we did in the first half it will not be easy to beat us," the England coach told BBC Sport.
"We deserved (to beat Croatia)," Eriksson added.
"I'm very proud of the the players. It is now important that we try to recover as quickly as possible and as intelligently as possible."
The Swede said: "We played very good football in the first half and controlled everything. It was a pity they scored.
"In the second half they started to create something but we played as we should like to play and if we do this on Thursday (in the quarter-final against Portugal) and in the future we should be very happy."
He added that he was pleased with the performance of Michael Owen, whose goalless tournament so far has contrasted to the free-scoring of his strike partner Wayne Rooney.
"Owen played well (against Croatia)," said Eriksson. "It was his best match of the
tournament so far and he was unlucky not to score a goal."
Captain David Beckham said England's positive state of mind was the key to victory.
"I think we showed a lot of confidence, especially in the first half," said Beckham.
"Even when we went 1-0 down, we were all over Croatia and we played our football which was important.
"We knew we'd break them down. With two players up front we knew we'd get goals."