Coach Inaki Saez said one mistake was all it took for Spain to throw away victory against Greece in Euro 2004 on Wednesday.
"We made our only error in the second half and it cost us a draw. We attacked well but we just weren't able to finish off some promising moves," Saez said after the 1-1 Group A draw.
"We had the game within our grasp."
Midfielder David Albelda said: "We have one loss of concentration and against a tough team like Greece you can't afford to make those sort of mistakes.
"Whatever happens now it's down to the Portugal game but then again that's what we came here for."
A 66th-minute goal from Angelos Haristeas cancelled out a strike by Fernando Morientes to give Greece a battling 1-1 draw with fancied Spain.
Greek goalscorer Angelos Haristeas said the draw showed Greece is a team to be taken seriously.
"This goes to show that the Portugal (2-1) win was not a fluke. This shows we are a serious team and that we have character and experience," he said.
"We will battle in every game. I believe in this competition everyone is nervous and everyone feels the pressure.
"In the second half we played like we were the favourites. Now we have played the two group favourites we have to go on and get a positive result against Russia."
