Chelsea manager Liam Rosenior has urged his players to eliminate costly defensive mistakes and improve discipline after a frustrating 2-1 Premier League defeat to Arsenal F.C..

Despite producing several promising attacking moments at the Emirates Stadium, Chelsea failed to secure points as defensive lapses during set-piece situations proved decisive.

Arsenal defenders William Saliba and Jurrien Timber both scored from corner kicks, exposing Chelsea’s weakness in defending dead-ball situations.

Rosenior admitted the defeat was particularly disappointing because his side had controlled parts of the game and created some of the clearest chances.

According to the Chelsea coach, recurring mistakes in concentration and discipline are undermining the team’s progress in the Premier League.

The situation worsened after winger Pedro Neto received two quick yellow cards and was sent off, leaving Chelsea to finish the match with ten players.

Rosenior noted that Neto had been causing serious problems for Arsenal’s defence before the dismissal.

The red card means the Portuguese winger will miss Chelsea’s next league match against Aston Villa F.C., further complicating the team’s push for consistency.

Rosenior stressed that while Arsenal have been particularly dangerous from set pieces this season, Chelsea must also take responsibility for their own defensive shortcomings.

He explained that the team had gone several matches without major disciplinary issues earlier in his tenure, but recent games have shown worrying signs, including multiple red cards in quick succession.

Chelsea’s disciplinary record has become a growing concern.

The club has now received seven red cards in the Premier League this season, with the number reportedly rising to nine across all competitions.

For Rosenior, the path forward is clear: improve concentration during defensive situations and maintain discipline on the pitch.

He believes that if Chelsea can address those two problems, the squad has enough quality to become a competitive side capable of achieving its goals this season.