Lionel Messi has admitted that Barcelona are "angry" and called for improvement after a 1-1 draw at home against Athletic Bilbao on Saturday.
The Argentine was a surprise absentee from the starting line-up, but was called into action in the second half after Oscar de Marcos had put the visitors ahead.
Messi hit the woodwork for the seventh time this season as Barca chased an equaliser following their 2-1 defeat at Leganes on Wednesday and 2-2 draw with Girona last weekend, eventually providing the cross for Munir El Haddadi's 84th-minute leveller.
"We are not anxious because the season is long and has only just started, but we are angry about the last results," Messi told Sky Sports. "We didn't expect them.
"Against Leganes we played well in the first half and lost, and today we created chances to win but couldn't.
"We are aware that we have to be much stronger defensively," added Messi, who inherited the Barca captaincy from the departed Andres Iniesta this season.
"Last year we hardly conceded goals but now teams are scoring against us with their first attempt. We cannot afford to concede goals in every game. We have to improve and become stronger in defence, which is the most important thing."