Arsenal narrowly beat Steaua Bucharest but finished second to Sevilla in Group H of the Champions League after the Spanish side saw off Slavia Prague.
Nicklas Bendtner celebrates after scoring Arsenal's second goal
Abou Diaby put the Gunners ahead when he pounced on Bacaray Sagna's cross.
Chances came and went for Arsenal, with Theo Walcott particularly wasteful, before Robin van Persie set up Nicklas Bendtner to slot home their second.
Steaua created little but pulled a goal back when Dorel Zaharia met Florin Lovin's cross with a looping header.
With his side's progress already guaranteed and Chelsea the next visitors to the Emirates Stadium on Sunday, boss Arsene Wenger understandably made changes and gave several fringe players the opportunity to impress.
They did not let him down, although it was relatively easy to shine against a side as lacklustre as Steaua.
The Romanians have picked up only one point in Europe this season and it was easy to see why.
Gunners keeper Jens Lehmann was one of the players Wenger had brought into his side but the German international had little to do apart from pick the ball out of the net after Zaharia had scored.
It was left to Arsenal to do almost all of the attacking and they came forward from the start.
Van Persie, back after a two-month absence with a knee injury, sent Walcott clear but the teenager's shot rolled agonisingly wide.
Walcott was in the thick of the action, with his pace and trickery creating several openings, but his finishing was consistently wayward and his final touch generally poor.
Openings kept coming for the home side however, and a goal seemed inevitable.
It duly arrived when Diaby reached Sagna's cross and powered his shot past Robinson Zapata.
Zapata did well to keep out a deflected Diaby effort soon after, and Van Persie curled another shot wide.
The Gunners kept up their pressure until half-time and were rewarded when Bendtner found the target, the Dane sprinting on to a Van Persie pass and clipping his shot into the bottom corner.
Steaua remained under the cosh for large periods of the second half too, with Arsenal threatening through a whipped Van Persie free-kick and Zapata coming out to deny Bendtner.
But, from nowhere, the Romanians replied when Zaharia met Lovin's cross, a goal that seemed to unsettle Arsenal.
Emmanuel Eboue had to clear from virtually under his own crossbar as the visitors pressed again and Ovidiu Petra also sent a shot whistling just past Lehmann's post.
Anything but a win would have been harsh on the home side though, and Arsenal soon recovered and got back to creating chances.
Zapata saved well from Bendtner, while Walcott and Eduardo missed late chances after running clear.
Arsenal boss Arsene Wenger on a potentially difficult draw for his side in the knockout phase of the Champions League:
"We could get a good draw and it could be an interesting match.
"We knocked Real Madrid and Juventus out two years ago and everybody is up for it this time.
"We had a good first half against Steaua and, although we dropped in the second, it is good to win after losing to Middlesbrough at the weekend.
Arsenal: Lehmann, Sagna (Diarra 70), Gallas, Senderos, Traore, Walcott, Song Billong, Denilson, Diaby (Eboue 70), Van Persie (Eduardo 64), Bendtner.
Subs Not Used: Fabianski, Toure, Silva, Adebayor.
Goals: Diaby 8, Bendtner 42.
Steaua Bucuresti: Zapata, Emeghara, Goian, Rada, Nesu, Neaga (Zaharia 64), Petre, Lovin, Cristocea (Surdu 56), Dica, Badea (Golanski 81).
Subs Not Used: Cernea, Bicfalvi, Baciu, Marin.
Goals: Zaharia 69.
Ref: Yuri Baskakov (Russia).