Mikel Arteta said that Arsenal must learn from conceding two sloppy goals against Bayern Munich if they are to have a chance of making it through to the semi-finals of the Champions League. Bukayo Saka’s 18th goal of the season had given the hosts an early lead before defensive lapses allowed Bayern to take a 2-1 lead at half-time through Serge Gnabry and Harry Kane’s 15th goal against Arsenal in 20 appearances. Gabriel Jesus and Leandro Trossard, on as substitutes, combined brilliantly to equalise 14 minutes from time to leave the tie delicately poised after Kingsley Coman struck the post late on. Saka confronted the Swedish ­referee Glenn Nyberg about not being awarded a penalty in stoppage time after claiming he was brought down by the Bayern goalkeeper Manuel Neuer, but Arteta insisted he had not seen the incident and instead said his players had missed an opportunity to establish a first-leg lead. “In the Champions League you cannot give anything to the opponent and we gave them two goals today,” the Arsenal manager said. “When you have this situation you are going to be punished. And that is the biggest lesson. The margins are very small in this competition and it is really difficult to create quality chances against this level of opposition. But I think the team showed a lot of composure, especially after 2-1 – you can throw your toys away and give your opponents a lot of space but we haven’t done that and the substitutes made a huge impact. “I sense the belief among the ­players that we are going to go to Munich next week and be better.” Thomas Tuchel was angry that Bayern were not awarded a penalty after Gabriel picked up the ball from a goal kick in the area. “It was a kid’s mistake,” the Bayern manager said of the incident in the 66th minute when his team were leading 2-1. Kane is now the leading scorer in the Champions League this season with seven goals, having taken his tally to 39 in 38 appearances since joining Bayern from Tottenham in the summer. The England captain clearly enjoyed his return to north London despite visiting fans ­having been banned from attending the first leg and he is looking forward to the second leg at the Allianz Arena next week. “We’ll probably be a bit more aggressive without the ball,” he said. “Having no fans in here tonight was really tough so to have a full stadium back in Munich will be incredible for us and I think they will really help us and push us on. You saw a real determined team – we had to show together­ness and show fight. Today was a small step in the right direction.”