BATE Borisov 1-0 Arsenal. It doesn't get much more embarrassing than that.
Stanislaw Drahun's goal separated the two sides in Belarus as Arsenal dominated the game but failed to take their chances.
Unai Emery's men had 16 shots at goal but only found the target three times, whereas BATE had six shots and managed to score from one of them.
A late red card for Alexandre Lacazette - who had a goal disallowed and later elbowed one of BATE's players - capped a hugely frustrating night for the Gunners.
Not even Pierre-Emerick Aubameyang could save Arsenal from defeat, with the Gabon striker coming on in the 68th minute alongside Lucas Torreira.
Loan signing Denis Suarez was also sent on by Emery in the closing stages but the Spaniard was once again anonymous.
Emery has a lot of decisions to make between now and the second leg next Thursday, such as which players to drop and which players to reinstate in the starting XI.
Bringing back Mesut Ozil would be a good place to start, because Henrikh Mkhitaryan was awful and Arsenal generally lacked cutting edge in the final third.
Another problem for Emery to address is corners. Granit Xhaka was the designated taker at the Borisov Stadium and not once did he beat the first man.
If one moment summed up how bad Arsenal were at set-pieces against BATE it was in the 67th minute, when they produced two abysmal corners in the space of 20 seconds.
Xhaka took the first one but fired it straight at a defender 10 feet away, and for the second, Mkhitaryan ran over, passed it to Xhaka, who teed up Kolasinac, who kicked it straight out of play.
OK, so the pitch was pretty poor, but these are professional football players earning over £100,000-per-week we're talking about here.
If only Arsenal had a world-class midfielder who could take their corners...News Now - Sport News