Greece manager Fernando Santos has insisted that his players need to keep their feet on the ground after their surprise progression to the knockout stages of Euro 2012.

Against the odds, the Greeks defeated Russia in their final Group A match to earn their first win of the competition and advance to the last eight. Captain Giorgos Karagounis afterwards said that nobody could stop them, although his boss has praised the team's character but believes that they must be realistic.

"Focus and concentration decided this match. We didn't allow our opponents to exploit their strengths and score a goal," said Santos.

"The character of the team emerged when they were in this situation and the reply was fantastic.

"[Russia] need a lot of space, especially in the last third of the pitch in order to create dangerous chances. So we needed to be very concentrated in not allowing them to deploy their skills and the talent they possess.

"From tomorrow we have to clear our minds and keep our feet on the ground. We know who we are, and we will give everything in the following match as well."

Greece will face Germany in the quarter-finals of the tournament.