A Dani Alves own goal has prevented Barcelona from taking a lead into the break against Spartak Moscow.
The hosts wasted no time in asking questions of the Spartak defence and they were rewarded for their early dominance in the 14th minute.
Cristian Tello collected a pass from Xavi before beating a defender and curling in a shot that left Andriy Dykan with no chance.
The Catalan club could have been further ahead just moments later but Lionel Messi failed to hit the target after a neat turn on the edge of the box.
However, Spartak found an unlikely equaliser on the half-hour mark when Emmanuel Emenike's dangerous cross was diverted past Victor Valdes by Alves.
Despite the setback, Barcelona continued to dominate possession and were unlucky not to restore their lead before half-time when Cesc Fabregas beat the offside trap, but the former Arsenal midfielder's header was well saved by Dykan.
