Pompey’s unbeaten run in the Papa John’s Trophy – including its previous guises – had stretched back for more than 1,000 days.
But an extremely youthful side were finally beaten 1-0 by West Ham U21s at an empty Fratton Park, with both clubs having already booked their place in the knockout stages.
Harry Kavanagh, Alfie Stanley and Charlie Bell all made their senior bow, while there were three more debutants from the bench.
Meanwhile, Harvey Rew and Eoin Teggart’s only previous taste of first team football came in the same competition last season.
And Kenny Jackett explained why he opted to give so many youngsters a chance in the Southern Group A fixture.
The Blues boss said: “It was a useful experience for us, with some of our senior players who needed minutes, getting them.
“We then had varying degrees of youngsters – from Haji Mnoga who made his league debut last week down to guys like Harrison Brook, who came on for his first ever taste of senior football.
“I felt that the congestion of the fixture list is a bit too much at the moment, so we didn’t want to risk anybody.
"There have to be opportunities for young lads and for them to be able to mix in and play in front of the coaching team."
“We wanted to get a clear run and have a few days in the week to give some of the guys a rest because we’ve had a lot of games, but also a lot of travelling.
“So my priority was always going to be going down to Plymouth next Monday, especially because we’d already qualified for the next stage of this competition.
“There have to be opportunities for young lads and for them to be able to mix in and play in front of the coaching team.”
Kai Corbett’s early strike was enough to secure victory for the Hammers and ensure that Pompey will be on the road in round two.
Jackett said: “It’s been difficult to integrate the younger players at the moment because of the Covid situation, so it was a great chance for them.
“But we faced a West Ham side who have worked together a lot as a team, while we were a collection of individuals at times.
“Our best opportunities were for Jordy Hiwula and the keeper had to make one fantastic save to deny him.
“We couldn’t get enough support up to him generally, although he showed he’s got pace and experience.”