Well, well, well. It appears as if the indomitable, invincible, insurmountable Atlético Madrid are not quite as in-_______ as reports would have you believe. Visiting Real Sociedad on Thursday, they suffered their heaviest defeat of the season, a 3-0 undressing that suggests, if nothing else, that our Europa League semifinal rivals are beatable. If we can do to them in this first leg what Real Sociedad has just done, maybe—just maybe—we can withstand whatever onslaught they'll mount in the second. There is no hubris here, no false optimism, only rational realism. Even as our own league form has dipped, we have to remind ourselves that we are marshaling resources (putting all of our eggs in one basket) and focusing on winning the Europa League. Real Sociedad has offered us an invitation, a dare, if you will, to at least get to the final.Let's put one rumour to bed right off: Atleti fielded a full-strength squad against mid-table Real Sociedad with the possible exception of Diego Coasta, that poor-man's Didier Drogba, who was injured and unavailable. Aside from his replacement, Kevin Aameiro , this was a full-strength XI, named to somehow close the gap between Atleti and Barça, but it was not be. Atleti's loss and Barça's draw with Celta Vigo have all but handed the title to Barça, leaving Atleti to fend off Real Madrid and Valencia to finish in second position.Without making too much of the maths, there is a slight advantage to the Arsenal. At our end, we have little to play for in the Prem other than perhaps pipping Burnley to finish sixth. As referenced above, the Europa League is our be-all and end-all. Yes, we do have the inconvenient matter of a Sunday clash with West Ham, but we should [shudder] see our way past them in order to prepare for Thursday's visit from Atleti.At their end, they have to recover from their Thursday loss to Real Sociedad quickly enough to host Real Betis, currently fifth in La Liga and on a fine run of form. It's not as if Atleti have anything to fear from Los Verdiblancos, but they do have to mind the fact that they're playing three matches in seven days. They've lost the first.As we assess our semi-final rivals, it's well-worth noting that they've qualified for Champions League play already. Even a complete collapse at their end would see them finishing no lower than fourth—currently on 71 points with five matches left, Real Betis can only rise to 70 points if they win out. Does this suggest that Atleti won't bring their best efforts to the first and second legs? We'd do well to assume that they will in fact bring their best.Then again, Atleti might just be entering that phase of the season that allows them to ease off the throttle—not that I'd suggest we count on that. They offer a much, much more-difficult challenge than any other squad we've faced in any stage of the Europa League competition. At a risk of slating the other side of the semifinal between Marseille and Red Bull, this clash between Arsenal and Atleti might just stand as "the" final. Whoever wins the aggregate has to be seen as the favourite to win it all. If we can batter them as Real Sociedad did and hold them off in that second leg, well, all bets are off: we might just add a bit of silverware to the trophy-case.What that means in the long run is another discussion for another day. For now, let's set our sites on battering the Hammers on Sunday. From there, we'll do as much as we can to play the role of rude hosts to our Spanish visitors. Something tells me we'll leave most if not all of our manners at the doorstep.