Lokomotiv Moscow 1 Barcelona 3
Javier Saviola scored twice to give Barcelona a third straight win in Europe and leave them on the brink of qualifying for the second stage of the Champions League.
The Argentinian youngster's double, and another goal from Patrick Kluivert gave the Catalans a historic first ever win in Moscow and their third consecutive win in Group H while James Obiorah scored Lokomotiv's consolation goal with an excellent solo effort.
Heavy afternoon rain in the Russian capital made for a wet playing surface, but both teams zipped the ball about slickly in the early stages.
Marat Izmailov and Dmitri Loskov, allowed Barca space on the ball though.
Xavi Hernandez had already forced a good diving save out of Sergei Ovchinkov with a long-range effort before Luis Enrique and Patrick Kluivert linked up to deadly effect in the 29th minute.
The pair have been lethal in both La Liga and in Europe this season and this time Luis Enrique nodded down a Gaizka Mendieta cross for Kluivert to bury the ball into the net for his second goal of this season's competition. Saviola struck three minutes later with a terrific flicked header after Xavi created the chance.
The double strike took the wind out of the Russians and from then until half-time Barcelona were able to play almost at will.
Saviola made the game safe in the 48th minute, controlling the ball on the edge of the 18-yard box and driving a low right-footed shot into the net.
But as Van Gaal began to think about changes, Obiorah gave Lokomotiv a glimmer of hope with the best goal of the game. The Nigerian, who was easily Lokomotiv's best player on the night, beat Carlos Puyol before lifting the ball over Victor Valdes to make it 3-1 and spark some life into his side.
Barcelona settled for a policy of containment, retaining possession and slowing the game down in the face of Lokomotiv's efforts, and they killed the match off expertly. Kluivert could have made it 4-1 in the 73rd minute when his left-footed drive hit the post from close range, but Barca did not need a fourth.