Arsenal vs Atletico, Marseille vs Salzburg in UEFA Europa League semi-finals

Arsenal vs Atletico, Marseille vs Salzburg in UEFA Europa League semi-finals

Atletico Madrid forward Diego Costa risks missing their Europa League semi-final games against Arsenal after he was diagnosed with a hamstring injury on Friday. The first leg will be played at OM's Orange VĂ©lodrome on Thursday, April 26 with the return leg to be played in Austria on Thursday, May 3.

Wenger, whose side play Man United away in the Premier League between the two semi-final legs, had identified Atletico, Champions League finalists in 2014 and 2016, as the most risky side in the draw.

The two joint-favourites to win the competition will face off in a huge semi-final clash.

And Le Saux believes two-time Europa League winners Atletico - second in La Liga, 11 points behind unbeaten Barcelona - will provide the sternest of tests for the north London side due to their thorough game-plan and defensive organisation.

LaLiga outfit Atletico reached the semi-finals 2-1 on aggregate, despite Thursday's 1-0 loss at Sporting CP in Lisbon.

The Europa League champion will get direct entry into next season's Champions League.

Diego Simeone's side are now second in LaLiga behind runaway leaders Barcelona.

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There is a lot riding on the Europa League for both sides.

However, they were knocked out of the respected group in the Champions League and have taken the competition by storm.

Yet in the quarter-finals, they seemed to become complacent after allowing Sporting back into the tie having not shown their usual clinical finishing.

Atletico progressed from their quarter-final 2-1 on aggregate against the Portuguese side, but former Chelsea striker Costa left the field in the 52nd minute.

Now, this is a tournament that means much more to Arsenal, Marseille and Red Bull Salzburg when it comes to next season.

The Gunners' 2-2 draw against CSKA Moscow in Russian Federation on Thursday night gave them a 6-3 aggregate win to put them within touching distance of next month's final in Lyon.