Elliott Dickman has admitted his side must be prepared to roll their sleeves up and show a nastier edge to their game from time to time.
On Monday night, Sunderland under-23s rounded off their group A Premier League Cup campaign with a defeat to Stoke City at Eppleton Colliery Welfare.
The visitors caught the Black Cats cold in the opening 45 to take a 2-0 lead into the break before Benji Kimpioka halved the deficit with a sweetly-struck free-kick from 20 yards.
However, Lee Connelly was then dismissed for a foul in the middle of the park before Thibaud Verlinen netted a late third to seal the win.
Speaking post-match, Dickman shared his frustrations over the defeat as he insisted his side must show a tougher side to their game.
"First half I thought we allowed them to play too much," said Dickman.
"We allowed them to have too much of the ball, didn't really put them under any real pressure.
"I'm quite frustrated with the first-half performance if I'm honest, I thought we were a bit nice and in danger of just letting the game bypass us.
"To be far we said to them at half-time, we wanted them to have a go and wanted them to press and make it a bit more difficult.
"I think the players did that second half so fair play to them for the reaction, but we made the job harder than what it should have been with how we started the game."
