Bialkowski made a stunning second-half save to deny Tom Huddlestone as Derby were beaten at home for the third time this season.
Ipswich must have sensed it was going to be another good night for them at Pride Park when Callum Connolly’s fifth-minute header struck the underside of the bar and crossed the line before Scott Carson clawed it out.
Derby were poor as Ipswich denied them space and, although they improved after the break, the visitors scrapped for everything and deserved the points.
Huddlestone’s deflected shot in the 50th minute looked to be going in until Bialkowski made a brilliant reaction save and Ipswich survived mounting pressure as Matej Vydra twice went close.
Derby should have scored when Johnny Russell went past two defenders before crossing but Joe Ledley ballooned his shot high over the bar.
McCarthy has never lost as a manager at Pride Park but knew the importance of Bialkowski’s stunning stop.
“Brilliant save, if there’s been a better keeper in this league for the past two seasons then I haven’t seen him,” said the Tractor Boys boss.
“Certainly at keeping the ball out and stopping shots, he’s fantastic. I thought we nullified them for the most part and when they did get through, we made some good last-ditch tackles and Bart made a great save.
“It’s a big win. I thought it was a really good, disciplined, well organised and stoical performance. If it was a team in the Champions League that had gone away, scored, sat in and been disciplined, people would be…