Arsene Wenger remained cautious about Arsenal's chances of reaching the Champions League final after a narrow victory against Villarreal.
Wenger believes Arsenal still have work to do in the second leg
Kolo Toure's goal gave Arsenal a 1-0 win in the semi-final, first leg.
Wenger said: "I believe it is a good result but we will know after the second game. We wanted a second goal but sometimes we were too nervous.
"We faced a good team, very strong in the midfield, and we couldn't impose enough to create more chances."
Wenger added: "At home you never know what is enough in a semi-final and it is difficult to go forward.
"We want to keep a clean sheet in the second leg, and we have proved we can do that, but it is not enough to just go there and defend. We want to play our game and score goals.
"We have got Spurs on Saturday and then the second leg of the Champions League semi-final - so the next six days will define our season - but we are confident we can do it."
The Frenchman also spoke of his disappointment at Villarreal's theatrical antics.
"They were very tricky in their attempts to break our attacks down," he said.
"I remember Alessio Tacchinardi going down at one point and he looked up to see if his side were on the attack. When he saw that they weren't he went back down.
"Tactically, they are very astute, very mature."
However, Villarreal striker Diego Forlan claimed his side had been denied a clear penalty in the first half when Gilberto Silva fouled Jose Mari but referee Konrad Plautz waved away the appeals.
He said: "I think the decision of the referee on Jose Mari - that was a big penalty.
"He didn't see that and I think he was against us all game. I think if you see it on TV it was.
"But it was not all about the referee. We didn't play well and we lost."