Although agreeing with Glenn Roeder that it is an extremely tough period, he says West Ham are always capable of hurting the better sides.
John, who is suspended for the trip to Old Trafford, says: "There are a few hard games coming up, with Man United and Arsenal next, but I have been in situations when we have had to win two of our last three games to stay up.
"We had Blackburn who were champions that year, Man United, and Liverpool who were second and fourth, and we won two of those and drew the other.
"There have been times when we were right in the mire and we have got better players now than we had then."
Despite the Hammers' current lowly position, he says: "The management has been great, the organisation and training has been great - we just need some luck and the confidence will come when the results do."
And, of the visit to the 'Theatre of Dreams', he insists: "There is an opportunity up there - they are not invincible by any means and are having a torrid time by their standards.
"We can get a result and we have to attack it with that in mind - we won't go up there thinking we are going to get beat, that is for sure.
"We mustn't go there like in previous years and think 'here we go' and try to hold out for a draw or whatever.
"Confidence wise they are not what they were so we have got to be positive."
A slight knee injury prevented him taking part against Aston Villa, but he says the atmosphere at the new look ground is as good as ever.
He refuses to blame it for West Ham being unable to win the last three games at Upton Park, and says: "I don't think it is the case because we haven't let in that many goals at home compared to away; we had a good run up until the Fulham game and we have only lost a couple at home.
"People criticised the atmosphere at the Spurs game but I thought the fans were great; there were more there and I certainly heard the noise.
"It's not like we have moved stadiums; it shouldn't affect us - we've not conceded many at Upton Park whereas away we have leaked them all over the place."
Squad: James, Hislop, Andersson, Schemmel, Winterburn, Minto, Repka, Dailly, Potts, Sinclair, Hutchison, Carrick, Cole, Courtois, Di Canio, Defoe, Camara, Garcia, Johnson, McCann.