Alexandre Lacazette was sent off as Arsenal suffered a shock Europa League defeat to BATE Borisov in the first leg of their last-32 tie, with Stanislav Dragun's header separating the sides.
Unai Emery's team spurned early chances in the first half through Henrikh Mkhitaryan and Lacazette, before BATE scored on the stroke of half-time as Igor Stasevich's whipped free-kick was headed powerfully past Petr Cech by Dragun.
In the second half, Lacazette had the ball in the net in the 56th minute but was ruled offside. Emery threw on Lucas Torreira, Pierre Emerick Aubameyang and Denis Suarez from the bench but to little avail and frustrations boiled over when Lacazette was dismissed for elbowing Aleksandar Filipovic in the 86th minute.
BATE: Shcherbitski (7), Filipovic (8), Rios (8), Filipenko (8), Volkov (7), Dragun (8), Hleb (6), Baga (7), Skavysh (8), Stasevich (7), Milic (7)
Subs: Berezkin (6), Dubajic (6), Moukam (N/A)
Arsenal: Cech (7), Mustafi (5), Koscielny (6), Monreal (5), Maitland-Niles (6), Xhaka (4), Guendouzi (5), Kolasinac (7), Mkhitaryan (5), Lacazette (3), Iwobi (5)
Subs: Aubameyang (5), Torreira (5), Suarez (4)
Man of the match: Stanislav Dragun
Arsenal began brightly and might have grabbed an away goal in the opening moments when Sead Kolasinac set up Mkhitaryan for a close-range chance that Denis Scherbitski in the BATE goal saved well.
Midway through the first half, Lacazette should have done better than head another Kolasinac cross over the bar. Dragun's goal was the first time Arsenal had conceded in the Europa League in six matches but came as BATE began to reassert themselves after their nervy start.
After Nacho Monreal had conceded a free-kick near the touchline, Stasevich whipped in the ball from the right flank and Dragun climbed above Kolasinac to beat Cech.
Arsenal fielded a strong side for the first leg; Cech was in for Leno, and there was just one more change from the side that beat Huddersfield 2-1 as Xhaka returned to replace Torreira.
For BATE, former Gunner Alexander Hleb started in midfield.
Alexander Hleb, in his fifth spell with BATE, and playing against his former club, lasted until the 58th minute. Two minutes earlier, Lacazette had slid the ball into the net from yet another Kolasinac cross but his effort was ruled offside.
With Arsenal struggling to find their rhythm, Emery threw on Torreira, Aubameyang and Suarez on from the bench, as BATE sat back.
With five minutes remaining, Lacazette reacted angrily to a challenge from Filipovic and swung an elbow towards the Serbian defender which resulted in a straight red card from referee Srdjan Jovanovic, meaning the Frenchman will miss the second leg.
- Arsenal have lost three of their last four away games in all competitions (W1), as many as they had in their first 14 combined under Unai Emery (W8 D3 L3).
- Arsenal are just the second English team to suffer defeat against an opponent from Belarus in European competition, after Everton in December 2009 (0-1 v BATE Borisov in the Europa League).
- Arsenal have been eliminated from each of their last six two-legged ties in European competition when losing the first leg - the last such tie they managed to reverse was against FC Porto in the Champions League in 2009-10 (6-2 on aggregate).
- Alexandre Lacazette's red card was the first shown to an Arsenal player in European competition since March 2017, when Laurent Koscielny was dismissed against Bayern Munich in the Champions League.
Man of the match - Stanislav Dragun
Dragun's 45th-minute header past Cech was the difference between the teams, and came after a well-executed set-piece move.
The midfielder had already made a contribution in calming Arsenal's initial dominance and was a key man in the defensive effort that saw BATE to victory.
Having gone out of the FA Cup, Arsenal now have a week off before the return leg against BATE at the Emirates on Thursday, February 21 at 5.55pm.