Dave Robertson has conceded that Peterborough United were simply "not good enough" in their heavy defeat against Charlton Athletic.

The Posh bowed out of the League Cup on the back of a 4-1 home reverse, prolonging their losing run to three games.

Robertson was left frustrated by the manner of each goal his side let in, suggesting that it is time for his players to "man up" if they are to turn their early-season form around.

"Disappointing is the word that sums up that performance," he is quoted as saying by the Peterborough Telegraph. "All the goals they scored arrived because of our errors and that's just not good enough. Goalkeeper Ben Alnwick dropped a cross for the first goal, Alex Davey has then slipped in the area and conceded a penalty.

"Harry Anderson gave the ball away for the third goal in a bad area and the fourth goal arrived on the counter attack from one of our own set pieces. Charlton are a very good counter-attacking team and showed some quality, but we have to do better. At times our own passing was good, particularly in the first half.

"Clearly there are a lot of things we must put right before we face a strong Gillingham side, but we will do just that. We can't make mistakes like we did tonight against teams with such quality. It's time for the lads to show some character and man up."

Peterborough return to action this weekend when they play host to Gillingham.