Arsenal head coach Unai Emery promised his team would "be different" for the second leg of their Europa League last-32 tie against BATE Borisov, but needed to "control the frustration" after losing 1-0 on Thursday.
Stanislav Dragun scored the only goal of the game on the stroke of half-time, and Alexandre Lacazette was sent off in 85th minute as Arsenal failed to find an equaliser.
"It's the first match," said Emery. "We are going to play another 90 minutes next week and I'm sure it's going to be different."
Lacazette's dismissal came after he aimed an elbow at Aleksandar Filipovic after the Serbian defender had fouled the France forward, who will miss the second leg.
The Frenchman would later apologise to his team-mates on Twitter and share his belief that they would still make it through to the last-16.
Emery said: "I didn't see the action but we need to control the frustration. It's bad news, this red card. Next week we won't play with [Lacazette]. But it gives chances for another player."
The Spaniard chose to look ahead to next week's meeting in London, adding: "Our big opportunity is next week at home. Today is not the result we wanted. We deserved more but they worked for this. Next week is going to be different with our supporters.
"We can win or lose but we play the second match and I trust in our work and preparations to make a different result at Emirates Stadium."
Emery defended a team selection that left Pierre-Emerick Aubameyang, Lucas Torreira and new signing Denis Suarez on the bench until the latter stages, with Mesut Ozil not even travelling to Belarus.
"Every player is OK to play," said Emery, explaining why he stuck with largely the team that beat Huddersfield 2-1 on Saturday. "Today those that were here, we can win with them and we deserved that.
"Last week we won and we played with the same players. For me today there was no difference to the performance. We deserved to win but didn't get the result.
"They were very organised defensively and they found the moment in the game," he said of BATE. "It's not for one player or another. We can win with every player and lose with the same players."