Arsene Wenger has conceded that he must strengthen his squad in the summer in order to challenge for honours next season.
A 2-1 defeat at the hands of Bolton Sunday seemingly put paid to Arsenal's hopes of winning the Barclays Premier League, and the failings of Wenger's squad were plain to see at the Reebok Stadium.
Each of Bolton's goals - the first from Daniel Sturridge and the winner from Tamir Cohen - came from Arsenal failing to adequately deal with corners and Wenger admits his side lack leadership when defending set pieces.
"We don’t attack the ball enough, nobody’s commanding," said the Arsenal boss.
"We made one mistake too many. It’s difficult to understand. We didn’t look alert. We concede two goals from two corners and, when you play for such a big stake, it’s too much.
"It is frustrating because you produce the effort. The team has had an outstanding attitude and they will not be rewarded because the small things cost you a lot."
The Gunners have been linked with summer moves for Trotters star Gary Cahill and Paris Saint-Germain centre-back Mamadou Sakho, and Wenger says he is already planning to reinforce his defence before next season.
He added: "We have to strengthen the squad where it needs and make the right decision on that front. It is always on my mind, every day. Don’t think it’s not on my mind."