Portsmouth striker gives details on his injury that's ruled him out of season opener

But the striker won't rush back from his calf injury and risk a prolonged period on the treatment table.

Harrison sustained his setback on the first day Kenny Jackett's troops returned from their summer break earlier this month.

It's meant he didn’t feature for the Blues in pre-season games against Norwich under-23s and Brighton.

While the former Bristol Rovers forward returned to full training on Thursday, he will be absent for the opening match of the campaign at Stevenage in the Carabao Cup first round tomorrow.

After being dogged by injuries during his year at Ipswich before moving to Fratton Park last summer, Harrison doesn’t want to go through the same experience at Pompey and is taking his time over a comeback.

He’s determined to put in the hard work to ensure he gets back up to speed, though, and able to make an impact when back to full fitness.

Harrison said: ‘I came in on the first day (of training) and tweaked my calf. I knew it wasn't going to be a long one so I'm just trying to get as fit as possible.

‘I was back out with the lads on Thursday and trying to get involved a little bit. At Ipswich, I was in the treatment room for long enough and it's the last place I want to be again when the boys are training hard.

‘It's almost like you're playing catch-up in pre-season. It's down to me to get as fit as I can while I'm out and when I get back in then I've got to work 100 times harder to get up to speed.

‘It's not a big one, touch wood, but you're always playing catch-up on the lads who've been training.

‘It's down to me to come back fit and it'll take a few games to get back up to speed fully, but if I carry on the way I'm going it won't take too long.

‘It's not ideal but it's down to me to get back fit. The target was to be back after two days but it doesn't work out like that!

‘I don't want to rush it and when the games come then hopefully I'll be back involved.’

Harrison is counting his blessing his injury isn’t going to sideline him for the long-term, however.

After watching Bryn Morris and Jack Whatmough absent for the majority of last season, the Welshman feels lucky he won’t be in that position.

Harrison added: ‘I've got to get on with it because lads like Whaty and Bryn have had injuries a lot worse than me.

‘They were in the gym every day and powered through sessions.

‘People have their low days because it's a glum place when you're in the gym stuck on the bike and the lads are out training.

‘That's hopefully in the past for me and I don't want to do that again.’