Gerard Pique' says their strenuous pre-season tour has had an effect on their season so far. Photo: Vincent West/Reuters

BARCELONA Barcelona defender Gerard Pique blamed the club's pre-season trips to the United States and Japan for their shaky start to the season.

The Catalans narrowly beat Villarreal 2-1 on Tuesday to provisionally move up to fourth in La Liga with 10 points from six games.

Barcelona have not won away from home all season and failed to keep a clean sheet in the league.

"We have not been able to train a lot, we have had many trips and it shows, there are players who are still not in form, others who have (injury) discomfort," Pique told reporters.

"The pre-season we had has not helped us, but this is Barca and there are no excuses."

Barcelona played Chelsea and Vissel Kobe in Japan in July, before heading back to Catalonia to host Arsenal in the Joan Gamper Trophy.

The Spanish champions then flew to the United States to play Napoli twice, in Miami and Michigan.

Six days later they travelled to face Athletic Bilbao in La Liga's opening game, where they capitulated to a 1-0 defeat.

Luis Suarez suffered an injury in the game and recently returned, but has struggled to find his best form.

Some supporters whistled the Uruguayan off against Villarreal as he failed to make an impact.

"I understand that fans have their opinion and express it, but I wouldn't pay too much attention to it," added Pique.

"We would like to win every game by four or five goals but it's not always possible."