At home to Championship side Blackburn. Wenger took a chance resting Cazorla, Walcott, and Wilshire, ahead of a stern mid-week Champion's League test away to Bayern Munich, and it cost the Gunners a chance at the FA Cup title. More specifically, Gervinho cost them a chance at the FA Cup by failing to convert a first-half chance that seemed more difficult to miss than to make. In the second half, Thomas Rosicky, who played a fine game, blasted a shot off Blackburn's crossbar. The shock was complete when Blackburn converted on nearly their only chance of the game on a scuffed follow-up shot, following a fine save by Szczesny.
Arsenal seemed to have possession of the ball for 80% or more of the game (although I'm sure the stats will show it was somewhat less than that). And they seemed to have several dozen corner kicks, most of which failed to clear the first defender.
But they couldn't find a way past Blackburn's stubborn defense, with a major assist from the wasteful Gervinho. In Gervinho's defense, Oxlade-Chamberlain was also poor, although he at least seemed to be working hard to create chances.
Arguably, the FA Cup was Arsenal's best chance for winning any silverware this season (having fallen out of the League Cup earlier against an even more downtrodden opponent). It is a measure of Wenger's excessive faith in his team that he thought he could get through this round without playing his strongest side, in favor of resting several key players for a mid-week clash in Munich in a competition Arsenal have much less chance of contesting.
I will not be the only Gunners fan shaking my head in dismay today.