AC Milan's Thiago Silva celebrates scoring a goal against Barcelona in the final minute to equalise during their Group H Champions League soccer match at the Nou Camp stadium in Barcelona Sept 13, 2011. [Photo/Agencies]

World's best

Milan were missing former Barca striker Zlatan Ibrahimovic, injured in training on Monday, among others, and coach Massimiliano Allegri opted to use Pato and Antonio Cassano in a two-pronged attack.

Pato threatened to score a second several times during the first half hour before fading out of the game, while Italy forward Cassano looked short on fitness and was replaced by Urby Emanuelson after an hour.

"Barca are still the best team in the world but sometimes even they can draw," Allegri said.

"That's why football is so great because sometimes you lose without deserving to and other times you win without deserving to."

Barca captain Puyol drew cheers when he came off the bench in the second half but their night was further soured by the injury to Iniesta.

The Spain international was forced off just before halftime and replaced by Cesc Fabregas and Barca said preliminary tests had shown he would be out for around four weeks.

"We try to look after the players as much as possible but these things can happen," Guardiola said.