Arsenal survived a brief scare before easing past CSKA Moscow with a 4-1 Europa League quarter-final first leg at the Emirates Stadium.
Aaron Ramsey gave the Gunners the lead in the ninth minute, shortly after seeing a goal ruled out for offside in the build-up, when he swept home Hector Bellerin's low cross.
However, the Russian outfit were level six minutes later through Aleksandr Golovin's superb free-kick from 20 yards which left goalkeeper Petr Cech with no chance.
Leicester loanee Ahmed Musa fired just wide as CSKA continued to hit the hosts on the counter before Alexandre Lacazette restored Arsenal's lead with a penalty after Mesut Ozil was brought down by Georgi Schennikov.