Barcelona coach Luis Enrique saw room for improvement but admitted his side had drawn strength from their 1-0 win at Athletic Bilbao on Sunday.
The champions have maximum points from their two LaLiga matches, with Ivan Rakitic's powerful header from an Arda Turan cross in the 21st minute proving to be the difference.
However, Barca were given a tough examination at San Mames and Enrique was pleased to head into the international break with a perfect record, despite missing the talents of Neymar and Andres Iniesta.
He told Diario Sport: "It is very difficult to play at San Mames. This is a result which really strengthens us.
"We were very serious in our approach and we put in a great physical effort. I think we could have finished the game off earlier than we did, but we put in a great performance. It was three points earned with great merit.
"We have started this season the way we finished the last - the players look engaged and want to set the sort of pace to make us the leaders. Although we are lacking some players at the moment, I see a great squad that is eager to compete."
Rakitic's goal could, and perhaps should, have been added to by Barcelona, but Luis Suarez wasted two good late chances to take the game beyond Athletic.
The Uruguayan had a chance laid on a plate for him in second-half injury time by Lionel Messi, but his lackadaisical effort was cleared by defender Eneko Boveda.
Athletic had chances of their own, and Benat Etxebarria should have done better early on when Barcelona 'sweeper keeper' Marc-Andre ter Stegen's misplaced pass gave him a chance to shoot.
There was a late claim for a penalty as Iker Muniain fell theatrically in the box under challenge from Rakitic, but they could not find a goal and are pointless after two games.
Athletic coach Ernesto Valverde told his club's official website: "Our idea was to keep the match alive until the end. We knew we had to keep pushing .
"We might have had a penalty, but I do not know because I have not seen the pictures yet. We have played two games played and have got no points, just like this time last year. We have to keep going."
Source: PA
