Persepolis took a step towards the final of the AFC Champions League with a 1-0 win at Al Sadd, earned thanks to a controversial 86th-minute penalty.

Ali Alipour stepped up to beat Saad Al Sheeb after he was brought down by the hosts' goalkeeper late in Wednesday's first leg of the last-four tie.

Qatar side Al Sadd, who started with Barcelona icon Xavi in midfield, were furious with the decision by referee Hettikankanamge Chrishantha Dilan Perera to point to the spot at Jassim Bin Hamad Stadium.

While replays indicated Al Sheeb caught Alipour as he raced through on goal, the contact was minimal and on the edge of the penalty area.

Iran international Alipour picked himself up to take the spot-kick and, although Al Sheeb guessed correctly by diving low to his left, he could not keep the shot out.

There was even more drama to come in the fourth minute of added time when Akram Afif thought he had scored a late equaliser for Al Sadd.

Afif challenged Alireza Beiranvand as the goalkeeper attempted to kick the ball out of his hands, the forward then rolling the ball into the empty net, but the goal was disallowed.

Al Sadd, last winners of the tournament in 2011, will seek to turn the tie around in the second leg, which is scheduled for October 23.