Cape Town - Arsenal defender Nacho Monreal says there is no room for error in the Champions League.
Arsenal play their opening game in the competition when they travel to Dinamo Zagreb on Wednesday evening.
Monreal is confident the Gunners will progress from Group F, but says concentration is vital when up against the best teams in Europe.
“You don’t play too many games so if you make a mistake you pay for it,” he told arsenal.com.
“You have to be really focused in each game and the level is higher. The difference is small but we have to be really focused.
“In every single game there is a lot of pressure [especially] when you play away, but we are accustomed to this so in this case it is more psychological than it is physical. It won’t affect us.
“We want to pass through into the next stage and we know that the favourite is probably Bayern Munich so we can’t lose against Dinamo Zagreb and Olympiacos as well.
“It would be really positive for us to start with three points as we will have more confidence in ourselves and it is the best way to start.”
The match at the Emirates kicks off at 20:45.