For much of last season, the French defender was linked with a move away from the club. Sagna's contract expires in 2014, and many expected Arsenal to take the final opportunity to cash in. As early as February, the Daily Mirror was suggesting he'd be on the way this summer.
Fortunately for Arsenal, the move didn't come to pass. The Gunners are now utterly reliant on their defensive stalwart.
During Arsenal's opening two games against Aston Villa and Fenerbahce, Sagna has played right across the defence. Against Villa, he started at right-back before switching to left-back. In Turkey, he again started at right-back before slotting into the centre after the injury to Laurent Koscielny.
Sagna is not hugely familiar with either role, but his experience and excellence allowed him to slot in with minimum fuss.
Today, at Craven Cottage, Sagna will once again be asked to fill a position that is not his default. In the absence of Koscielny and Thomas Vermaelen, Sagna will partner Per Mertesacker at centre-back.
It's mildly ridiculous that Arsenal, a club with enormous resources, are in a position where they go into a Premier League game with just one fit centre-half. The club have known about Vermaelen's back injury for almost two months now, yet have failed to bring in a replacement.
Instead, they have allowed both Johan Djourou and Ignasi Miquel to leave on loan. Incredibly, the club have reacted to the blow of losing Vermaelen by further reducing their options.
Arsenal have spent the summer being linked with a variety of big names, but few have been centre-backs. It would be folly not to bring one in. It may not be the most glamorous position on the pitch, but it is one of the most important.
During preseason, Sagna was frequently used as an option in the middle. He auditioned for the role with a man-of-the-match performance at Sunderland last season.
Manager Arsene Wenger clearly believes he has a future there, although his willingness to rely on Sagna is a concern for Arsenal fans. The Frenchman remains comfortably the squad's best right-back, and moving him to the centre means weakening other areas of the defence.
Today, Carl Jenkinson will be asked to slot into Sagna's usual position. The young full-back enjoyed a terrific start to to last season and will be hoping that Sagna's temporary displacement affords him another opportunity to impress.
However well Jenkinson does, it seems likely that Sagna will return to right-back once Koscielny has finished his suspension.
Arsenal may not consider Sagna important enough to offer him a new contract, but without him it seems their defence would simply fall apart.