Mark Lillis hailed his side’s attitude, but admitted poor defending cost them at Cardiff City.
Having gone behind to goals by Peter Whittingham and Kenwyne Jones, a Murray Wallace strike in first-half stoppage time gave Town hope.
But Trinidad and Tobago ace Jones sealed City’s win with a 56th-minute strike in front of 20,749.
“That third goal was a killer blow,” said Lillis. “It was a great finish, but also a bit of poor defending.
“When we got the goal just before half-time, we came back in and the dressing room was bubbling. We thought we could get a result.
“But when you make mistakes, good sides like Cardiff will punish them.”
Lillis, who played a midfield diamond, hailed the performances of debutant Jacob Butterfield, Town’s £750,000 buy from Middlesbrough, and ex-Liverpool player Conor Coady, who made his first league start for Town.
“I was pleased with what they did and both will be fantastic players for this club,” said the academy chief.
“I thought the system worked to start with, but we were lacking a little at both ends of the field.
“I was really disappointed to go two down after starting strongly.
“It was the same at Chesterfield (in the Capital One Cup) and we have to address that and be better.”
Town head to Reading tomorrow, and Lillis added: “We’re getting into the right positions in the final third, but we have to be more clinical.”
Lillis hopes to have skipper Lee Peltier back after a groin injury kept him out at Cardiff, but frontman Joe Lolley has a hip problem and had been advised to rest for 10 days by a specialist.
Town are also missing James Vaughan and Anthony Gerrard (both calf), Oscar Gobern (toe) and Martin Paterson (knee).
Cardif boss Ole Gunnar Solskjaer said Town caused his side problems early on.
“We weren’t expecting the system they deployed with the crowded midfield, so we had to change things,” said the Norwegian, who has signed former Town players Anthony Pilkington and Sean Morrison.
“Kenwyne Jones has been working hard this summer. He’s still not fit enough to play 90 minutes but he does cause the opposition problems.”
