On 25 January 2011, Koscielny scored the second goal in the 3–0 win over Ipswich Town in the League Cup semi-final second leg win at the Emirates Stadium. Throughout January 2011, Koscielny and Johan Djourou were a part of a defence that did not concede a goal in the Premier League. On 1 February, he scored his third goal of the season, which proved to be the winner in a 2–1 turn around victory over Everton. Koscielny had arguably his best performance to date for Arsenal in the first leg of the Champions League round of 16 match against Barcelona. The match ended in a 2–1 home win for Arsenal. Koscielny's performances were applauded and praised in many media reports of the game. Former Arsenal defender, Martin Keown, said his performance was "impressive" and "magnificent throughout". On 27 February, in the last minute of the 2011 Football League Cup Final, Koscielny was involved in a mix-up with his goalkeeper Wojciech Szczęsny, which resulted in Birmingham City striker Obafemi Martins scoring the winning goal.