?Barcelona's supporters celebrate after their team won the Spanish league title at Canaletas fountain at Ramblas in central Barcelona on Wednesday. Gustau Nacarino / Reuters

Barcelona coach Pep Guardiola praised his weary players after watching them win a third successive league title with a 1-1 draw at Levante on Wednesday and said it had been even harder on the back of the 2010 World Cup.

Barcelona won the league with two games to spare to retain the title and become the first team to win three straight league crowns since 1993 when Johan Cruyff's great Barcelona 'Dream Team' won the third of four consecutive championships.

"It has been a difficult league, just like the last one was. If we are champions it is because we deserve to be," said Guardiola.

"It is our fifth league title in 10 years and I ask the players to celebrate it with their families as you can't forget these things."

Guardiola admitted his team had struggled to maintain high standards in recent months but pointed out that a number of his players had arrived worn out after playing the entire World Cup in the summer as Spain tasted glory in South Africa.

"We were fantastic for the first three quarters of the league and in the final quarter the goals dried up," said Guardiola.

"If we have dropped our standards at the end of the season it is simply because the team has barely stopped for the past two seasons.

"It was difficult coming off the back of the World Cup. Nine Barcelona players won the World Cup (with Spain) and I didn't know how they were going to react. The attitude of all the players has been fantastic and the title is for them."

Barcelona is now targeting a league and European double as it switches its focus to the Champions League final against Manchester United at Wembley on May 28 - a repeat of the 2009 final which Barcelona won.

"We can celebrate now and then prepare for the most beautiful game of the season which is the Champions League final," said Guardiola.

Spanish World Cup winner David Villa, a 40 million euro signing from Valencia, echoed the sentiments of his manager after lifting his first league title with Barcelona.

"This is the result of nine months hard work," said Villa. "Now we have to celebrate it and think about the Champions League final at Wembley."

Barcelona has been hailed as the greatest team on the planet with some saying it is among the best sides of all time, but Guardiola insisted there was still room for improvement.

"We have to reinforce in certain areas and there are things we can improve on," hesaidd.