In a largely uneventful match at Fratton Park, the hosts struggled to carve out any clear-cut chances on a frustrating afternoon.
As a result, today's shutout has dented their faint play-off hopes further, with the gap between them and the top-six remaining eight points, with eighth matches of the season remaining.
Although gaining a total four points from a side relegated from the Championship last term could be seen as credible, the Blues skipper explained how their performance fell short of the standard set at the club.
He told The News: ‘We need to win every game when you’re at Pompey because it’s a big club. The expectations are high and you’ve got to be winning your home games. From that point of view, it’s probably two points dropped (today).
‘It’s going to be difficult (to get into the play-offs), but we’ve got to keep fighting and try and get three points in the next game. We’ll take each game as it comes and see where it will take us next season.
‘We’ve got eight games left and we know it’s going to be difficult. We won’t give up until it's over and we need to keep fighting and stick together.’
When examining the statistics of today’s draw, it could be argued that the visitors had the better of proceedings – as they had four times Pompey’s shots on target.
Gareth Ainsworth’s side are firmly in the hunt for the promotion as they sit one point behind current sixth place occupants Sunderland.
This may be down to the Chairboys maintaining the core squad that was relegated from the second tier last season – which, in Robertson’s eyes, was reflected in their performance.
He added: ‘I thought it was a difficult game, you always know what you’re going to get with Wycombe. I don’t think we were at our best today and it was difficult.
‘We didn’t really get into our stride quick enough in the game. Wycombe are a direct, physical team and we had to deal with that, but we probably didn’t create enough chances going forward.’
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