Birmingham manager Pep Clotet insisted he had no regrets over his team selection after his youthful side slumped to a 3-0 Carabao Cup first-round defeat at League One Portsmouth.
Ellis Harrison's home debut double and Ben Close's thumping long-range volley sent Championship City crashing at Fratton Park.
Clotet made nine changes from Saturday's 1-0 win at Brentford including a debut for 16-year-old Jude Bellingham, who broke Trevor Francis's record as Birmingham's youngest ever player.
Clotet said: "I am not happy with the result, like anyone shouldn't be, but I focus on the positives.
"Not only do the players who did not play have the right programme for Saturday, but we have bright young talent coming through and they need these opportunities.
"I hope Jude is the one making the headlines and not the results because he is a great talent and has a big part to play in the future of our club."
Pompey took a deserved lead after half an hour when Harrison's close-range header had been adjudged to have crossed the line before Wes Harding cleared the ball onto his own crossbar.
Midfielder Close made it 2-0 with an emphatic 22-yard volley five minutes before half-time.
Harrison grabbed his second and Pompey's third nine minutes after the break by heading in a Ronan Curtis cross at the far post early in the second half.
Portsmouth assistant manager Joe Gallen said: "It was a terrific performance. We played very good football.
"After the first goal you could see the confidence come back very strong.
"Ellis Harrison scoring two goals on his full debut is great. All in all, it was terrific for us and gets our season off and running.
"They made nine changes from Saturday but that is not our problem. Physically and technically it was a very good performance tonight."