Despite a 1-0 win over Bolton which puts them within reach of the comfort zone, Hart - who has collected 13 points from his eight matches in charge - insists they must pull out all the stops to give Manchester United major problems on Wednesday.

Hart's dedication to basic defending means match-winning substitutes Kanu and Nadir Belhadj are almost certain to be on the bench again at Old Trafford, despite an ankle injury which looks set to rule out a leading creative force in Niko Kranjcar.

Kanu claimed his first league goal of the season in the 78th minute on Saturday after blocking off Bolton's heroic goalkeeper Jussi Jaaskelainen and applying a final touch to Belhadj's viciously inswinging corner.

It gives Pompey 37 points with just six games to go, seemingly out of reach of the bottom three, but with the next three games against United, Newcastle and Arsenal, Hart insists the job is far from complete.

He said: "If you can hazard a guess where it will all end up you are a better man than me.

"We could possibly be needing 40 points but I think there's no reason we can't go to Old Trafford, make their life very difficult and get something.

"I just want us to get our heads down again and carry on. If you just think about the last result you'll get nowhere except an early grave.

"What we concentrate on is not giving goals away and, apart from the West Brom game where we still scored two goals, I've had no complaints.

"We've just tried to be tough to beat and I think I can honestly say we could have won every one of the eight games I've been manager.

"And now we are not going anywhere just to lie down. Don't get me wrong, Manchester United are the best team in the world but there's no way we are going there and rolling over - I hope."

Pompey won 1-0 at Old Trafford in the FA Cup quarter-final last season but stars like Lassana Diarra, Sulley Muntari and Pedro Mendes who went on to win the trophy have gone.

Kanu, who scored the winner in both the semi-final and final, has started just four times this season, two of those in the UEFA Cup where he scored his only other goal of the campaign against AC Milan.

Yet his total of 21 appearances may already be enough to activate a clause in his contract which earns the Nigerian, 32, the right to another one-year deal next season.

Kranjcar, outstanding on Saturday until felled by a challenge from Gavin McCann, faces a scan on his damaged ankle and may miss several games.

Bolton boss Gary Megson also has a new injury problem with Ricardo Gardner carried off after just 11 minutes and, like Hart, certainly believes his own club's status is not guaranteed.

He said: "Last year people said we were gone after a 4-0 defeat (at Aston Villa) left us in the bottom three with five games to go, but we won three and drew two to get out of trouble and there is always the fear somebody else is capable of doing that.

"We've just got to make sure we are not the ones who get caught but we've got to do a lot better than against Portsmouth to be sure of that.

"We just didn't play how Bolton play and I can't think of many of my players who performed anywhere near the way they should."