While Cesc Fabregas’ integration into Barcelona’s squad has gone smoother than expected, the club’s decision not to bring in new defensive players this summer was exposed again in a 2-2 draw at Valencia.

Coach Pep Guardiola again turned to a 3-4-3 formation on Wednesday but Valencia took advantage of that system during a first-half blitz to lead 2-1. Guardiola returned to a 4-4-2 formation after the restart and Barcelona regained control before Fabregas netted a late equalizer with his fourth goal.

But it wasn’t enough to prevent Barcelona’s third 2-2 draw in two weeks.

While Barcelona bought Fabregas and Chile forward Alexis Sanchez in the off season, no defenders were brought in despite Carles Puyol having missed much of 2011 with a knee injury and fellow center back Gerard Pique out injured to start the season.

“The start to any season is always difficult but I think we made an important push, especially in the second half,” Fabregas said. “This team has well-known mechanisms and we try to use them as best as possible. I try to take advantage of my teammates qualities.”

Fabregas and Messi have carried much of Barcelona’s attack this season, starting with the former Arsenal playmaker’s first appearance in the return leg of the Spanish Supercup, when he fed the Argentina forward for the late winner. The pair have combined for nine goals.

But while the former youth academy teammates are linking up well, Guardiola’s makeshift defensive formations aren’t.

Javier Mascherano looked out of place covering the left flank as Jeremy Mathieu and Jordi Alba’s pace exposed the Argentina midfielder, with Mathieu delivering crosses to set up both goals.

“We were ready for two tactical systems and that was one of them, and it’s true it suited us better in the first half,” said Mathieu, who believed the absence of Puyol and Pique in the middle of defence is Barcelona’s biggest worry. “They have a lot of injuries, they haven’t had the Puyol-Pique tandem either, so maybe when they’re back they will be even tougher. But Puyol is not 100 percent, I think he still needs time to find his rhythm. He was in trouble a couple of times.”

Puyol has played only a handful of times since injuring his left knee in January, but returned earlier this month from surgery.

“Every day I feel better, the knee is responding well. I don’t feel any discomfort,” Puyol said. “Every week is difficult, teams are preparing for our games very well and every time it’s harder.”

Barcelona have conceded six goals in four games, and allowed a late equalizer to give AC Milan a 2-2 draw in the Champions League last week. The previous weekend, they wasted a 2-0 lead at Real Sociedad in the Spanish league.

Pique is expected to return to play tomorrow against Atletico Madrid, whose new signing Radamel Falcao has scored five goals so far to lead the league alongside Messi and Roberto Soldado.

And while Barcelona have struggled defensively, they are still doing better than Real Madrid, who have their own problems in attack. Madrid’s 0-0 draw at Racing Santander on Wednesday left the Spanish giants one point behind Barcelona in the standings.