Alexandre Lacazette was sent off for elbowing Aleksandar Filipovic and also had a goal disallowed as Arsenal slumped to a disappointing first-leg defeat against Bate Borisov in the Europa League last 32.
Stanislav Dragun scored the only goal just before the break, to seal a shock victory for the hosts.
The Belarusian champions held on for the win which happens to be their first win over an English side at home in European competition and they will now take a slender lead to the Emirates for the second leg next Thursday.
For Chelsea, Ross Barkley and Olivier Giroud scored as Chelsea beat Malmo 2-1 in their own fixture in Sweden.
The win provides a bit
In other matches, Benfica won 2-1 at Galatasaray, Rapid Wien lost 1-0 at home to Inter Milan, Sevilla defeated Lazio 1-0 and Valencia recorded an impressive 2-0 victory over Celtic.
