Nemanja Vidic has warned his Manchester United team-mates not to dwell on a disappointing start to their Premier League title defence.
United head to Portsmouth this evening already two points adrift of their major rivals following the goalless draw with Reading on Sunday.
The Red Devils' failure to take just one of the 20-plus chances they created against Steve Coppell's men was only exacerbated by the fractured foot sustained by Wayne Rooney which will rule him out of action for two months.
But Vidic does not believe there is any point worrying about events United can do nothing about.
'We have dropped two points already and we are disappointed with that,' said the Serbia defender.
'But we cannot afford to think about it too much. It is a long season, so all we can do is assess where we made the mistakes and try to improve.
'Portsmouth are always a difficult team to play against anyway, so we cannot afford to go into the match still thinking about what happened against Reading.'
Vidic admitted the loss of Rooney is a hammer blow, although the former Spartak Moscow man is convinced United have the players to cope with his absence.
'Wayne is a big loss because he has been in such good form during pre-season,' he said.
'Hopefully, he will be back quickly but we have a big squad, with lots of competition for places and there are plenty of others who have the ability to score.'
Sir Alex Ferguson has already confirmed Argentina forward Carlos Tevez, who finally joined United on a two-year loan at the end of last week, will replace Rooney.
Given the weekend's results, United's need for victory is obvious, even at this early stage of the season.
Yet Ferguson will not need reminding his side have lost on three of their last four visits to Fratton Park, and with Harry Redknapp striking a blow for veteran bosses by guiding Pompey into their highest league placing for over half a century last term, United are in for a tough test.
'Fratton Park is not an easy place to go to,' Ferguson said.
'It means Portsmouth have a big advantage overall in terms of their likely home record.
'Harry has made a few interesting additions too, especially David Nugent, John Utaka and Sulley Muntari, who we have watched quite a bit, and I would expect improvement from them this season.'