The Pompey winger served up a tantalising glimpse of his quality with his maiden goal for the Blues, in the 2-1 Carabao Cup loss at The Den.
Hackett-Fairchild smashed in an excellent fourth-minute drive on his first start in 20 months, before the Lions came back to grab success.
There was a chance for the 23-year-old to win it late on as his effort was cleared off the line by Ryan Leonard.
Hackett-Fairchild confessed he thought he’d scored on a showing of promise on just his third appearance, since signing from Bromley at the start of 2020.
He said: ‘I got the opportunity, ran at him and had a go for the goal.
‘Then I thought I’d got a second.
‘I thought when the keeper came out and it squirmed through the legs it was in.
‘Then the second one was cleared off the line.
‘My eyes lit up when it came back to me and I thought I’d done enough.
‘So that was disappointing but I was pleased with how I did.’
Hackett-Fairchild felt Pompey’s performance warranted a return against second-tier opposition, as they played the majority of the second half with 10 men.
They withstood pressure at times after they lost their way following a bright opening against Gary Rowett’s side.
Hackett-Fairchild was certainly among his side’s brightest performers, and he admitted he’s been desperate to show Pompey fans what he can do.
He added: ‘It was hard being down to 10 men but we worked hard and held our own.
‘We nearly nicked it at the end and I felt we deserved that goal.
‘We didn’t have loads of the ball and dominate the game but I felt we were slightly unlucky to lose it.
‘It’s been a while for me and I’ve been itching to get out there in front of the fans.
‘I’ve had few opportunities in pre-season and now it’s the business end.
‘It was great to be out there and to get a goal topped it off really.’