Arsenal boss Mikel Arteta admits they need to tighten up at the back.
The Premier League leaders are at Fulham later today.
Arteta said, "We conceded two goals against Bournemouth and against Sporting. If you want to be at the top, win and win and win, you need the goals.
"We were really good at preventing chances, but not enough in the last two weeks and we didn't do the right things in the box.
"The first leg? We were in total control of the game, we made a huge individual mistake which cost a goal, but the team reacted as they reacted all season."
