Who could Arsenal face in the Champions League play-offs?

Whilst Arsenal secured fourth place in the Premier League on Sunday, they still have a couple of matches to negotiate before they make the Champions League group stage. Who could they face in their qualifying tie?
Although the Champions League play-off round is generally a nuisance, rather than a genuine threat to English team’s hopes of making it into the group stage, there have been a couple of recent occasions when teams have come close to falling at the final hurdle.

Tottenham Hotspur made a meal of beating Young Boys Bern in their one venture into the Champions League, whilst Arsenal themselves had a couple of jitters against Udinese the last time they had to qualify.

The format now means Arsenal go straight into a play-off round, in which there will be twenty teams in total facing off for the last ten spots in the group stage. Five team go straight into this round, with Arsenal already joined by Schalke, AC Milan, Portuguese team Pacos de Ferreira, and set to welcome either of Real Sociedad or Valencia from Spain

Are we going to get in or get out ARSENAL?