Arsenal edged into the semi-finals of the Europa League, but only after surviving a major scare as CSKA Moscow threatened a memorable comeback.
Leading 4-1 from the first leg at the Emirates Stadium, the Gunners appeared set for routine passage into the last four, only for CSKA to outplay them in Russia.
Danny Welbeck's fifth goal in five games checked CSKA's progress after Fedor Chalov and Kirill Nababkin had pounced on Petr Cech parries to put the hosts within touching distance of an unlikely turnaround.
Aaron Ramsey scored in stoppage time to seal a 2-2 draw, sending Arsenal through 6-3 on aggregate.
While Arsenal supporters enjoyed a trouble-free day in Moscow, the same could not be said for their side on the pitch, with their poor away form again laid bare.
There was a mixture of sloppiness and nervousness in the opening half-hour, with Arsenal clearly keen not to ship an early goal as so many teams with commanding leads had done in Europe earlier in the week.
While Shkodran Mustafi and Mohamed Elneny were particularly guilty of a couple of shaky moments, the hosts could not capitalise, despite Ahmed Musa's pace again causing problems.
CSKA took a deserved lead soon after losing playmaker Alan Dzagoev to injury, Chalov tapping home after Cech had done well to get down and keep out Nabakin's header but could only push the ball into the path of the young Russian forward.
Kristijan Bistrovic struck an effort just over Cech's crossbar soon after as Viktor Goncharenko's side went in search of a second goal to really open up the tie.
Ramsey was carried off on a stretcher as the evening threatened to go from bad to worse for Arsenal, with Jack Wilshere also suffering a knock on the stroke of half-time. Both, though, were able to continue.
Arsene Wenger made a tactical tweak at the interval, dropping Elneny into defence, but it made little difference early on as Nabakin was this time the beneficiary of a Cech parry, turning home after the Arsenal goalkeeper had failed to hold Aleksandr Golovin's effort.
Cech did much better moments later as he turned a well-struck Golovin free-kick behind, with CSKA well on top.
Elneny, now back in midfield after the short-term measure, saw a header correctly chalked off for offside as Arsenal finally managed to string a cohesive attack together.
Laurent Koscielny blazed a difficult chance well over the bar as Wenger introduced Calum Chambers in place of the ineffective Wilshere in an attempt to close things out at the other end.
Arsenal's breakthrough came seemingly out of the blue, Welbeck finishing superbly past Igor Akinfeev, who had not been forced into action until that point, after an inch-perfect through-ball from Elneny.
Welbeck had another effort smartly saved by Akinfeev before Ramsey clipped home an equaliser at the death to give Arsenal a result they barely deserved as they seek a return to the Champions League by lifting the Europa League trophy in Lyon next month.