Stuart McCall believes leaders Pompey are the best team League One has to offer.
The Blues were 2-1 winners at Glanford Park on Saturday, extending their advantage at the summit to four points.
First-half goals from Tom Naylor and Gareth Evans looked to have put Kenny Jackett’s side on the way to a convincing victory.
But after Lee Novak got one back on the hour mark, it was the Iron applying all the pressure.
Yet Pompey remained resolute to ensure they returned to Fratton Park with a 10th away success of the campaign.
McCall was pleased with the fighting spirit his Scunthorpe troops displayed.
But the Iron boss insisted his side have a long way to go to get to the Blues’ level.
McCall told Scunthorpe’s official website: 'We were 2-0 down against the best side in the league, as the table shows, who are outstanding away from home.
‘They’re a good side, no doubt, but the key is to try to get the first goal against them. They got that from a set-play which they’re really strong at.
‘We didn’t win the first header or the second ball, which is crucial and then they got one again not long after.
‘It was a good goal from their point of view. One of our forward players dropped a runner and Gareth Evans nicked in, which we’re always aware of and we showed that lads him doing that in the video on Friday.
'It could have been a case of do we buckle and it ends four or five nil, or do we show a bit and go out and win the second half.
‘They did that and for spirit, guts and effort, it was terrific against a side with an experienced manager and a lot of lads who know this level.
'We’re not at Portsmouth’s level at this moment and we have a lot of work to do to get there, but one day we’ll be there.’