Neil Harris said the performance of Ben Thompson was one of the few positives he took from Saturday’s 4-0 defeat to Coventry.
The midfielder replaced Lee Martin at half-time and gave some much-needed urgency to his side.
He also showed a willingness to get forward and shoot, with one effort from 25 yards forcing Coventry keeper Lee Burge into a full-length save.
Harris said: “If you’re asking for positives then there was Ben Thompson, who I thought did really well.
“I think he showed the whole squad what it means to represent this club and, just as importantly, what it means to him to represent Millwall.
“I was really pleased for Ben, he really impressed when he came on with his pace and energy in the middle of the park.
“And he certainly showed courage to get on the ball.”
Sky blues boss Tony Mowbray, meanwhile, defended Lions keeper David Forde after the Irish international had been lobbed by striker Adam Armstrong for Coventry’s opening goal.
The keeper has been criticised by the home crowd this season, but Mowbray preferred to emphasise the quality of his on-loan Newcastle forward.
“I think Forde’s been a very good goalkeeper for his club, he’s been around a while,” Mowbray said.
“Armstrong deserves great credit for his goal. A few minutes earlier Forde had come out of his goal playing like a sweeper-keeper, assuming he’d thought that because Armstrong is so fast he has to help his defenders.
“That happened two minutes before Armstrong received it 40 yards out and he didn’t even look, he knew the keeper would be off his line. That just shows his quality.”