Cesc Fabregas and Alex Hleb scored a goal each to give Arsenal a strong advantage over Sparta Prague in their Champions League third-round qualifier.
Arsenal players congratulate scorer Cesc Fabregas
Arsenal struggled for fluency at times and almost conceded on nine minutes when Jan Rezek's volley hit the post.
And the Gunners barely threatened early on as fouls outnumbered chances.
But Fabregas slotted in from the edge of the box on 72 minutes and Hleb put the finishing touch to a counter-attack on 90 minutes to seal the victory.
It was just about deserved as Arsenal steadily improved after the interval.
But boss Arsene Wenger will be concerned that his side appeared to struggle initially when faced with physical opponents.
Sparta - beaten in each of their four previous Champions League matches against Arsenal - were quick to flex their muscles, biting into the tackle and trying to bully the visitors' lightweight midfield.
It cost them two quick bookings as Lubos Husek and Marek Kulic were punished for over-zealous challenges.
However, the tactics did seem to rattle the Gunners and Sparta grew in confidence, zipping the ball around the greasy surface and trying to pull Arsenal out of position.
They succeeded fairly quickly as Pavel Horvath's cross drifted beyond left-back Clichy and Rezek showed great technique to volley sweetly, but was denied by the upright.
And if Arsenal were less than impressive defensively, their attack was virtually non-existent.
A Fabregas shot and a Robin van Persie free-kick - both easily dealt with by keeper Tomas Postulka - were the visitors' only chances of the half.
Worryingly, Fabregas' biggest contribution was a clumsy tackle on Tomas Repka, which the former West Ham defender failed to recover from and was later forced off injured.
In keeping with a game of more fouls than passes, three Arsenal players - Fabregas, Matthieu Flamini and Van Persie - ended up with yellow cards in the opening period.
After the break, Arsenal mixed a little more silk with their new-found steel, and Van Persie turned on a sixpence to get in a shot which tested Postulka.
But still there was a lack of ideas - from both sides - and little goalmouth action until defender Clichy took matters into his own hands.
The Frenchman skipped past two challenges and laid the ball off to Fabregas, who finished smartly.
Briefly, Sparta responded well and Martin Abraham had a claim for a penalty when he fell over the leg of Fabregas.
But in the last minute of normal time, Arsenal launched a rapid counter-attack.
Bacary Sagna stormed down the left flank before passing inside to Hleb, whose slightly scuffed shot still had enough pace and precision to beat the keeper.
Sparta Prague: Postulka, Repka (Brezinsky 36), Kadlec, Kladrubsky, Abraham, Husek, Horvath (Limbersky 86), Pospech, Dosek, Kulic, Rezek (Matusovic 59).
Subs Not Used: Kozacik, Slepicka, Kisel, Zofcak.
Booked: Husek, Kulic.
Arsenal: Lehmann, Sagna, Toure, Gallas, Clichy, Eboue, Flamini, Fabregas, Rosicky (Song Billong 80), Hleb, Van Persie.
Subs Not Used: Almunia, Senderos, Bendtner, Traore, Justin Hoyte, Walcott.
Booked: Fabregas, Flamini, Van Persie.
Goals: Fabregas 72, Hleb 90.
Ref: Luis Medina Cantalejo (Spain).