Zola, who will use Guillermo Franco as his target man in place of the injured Carlton Cole, said: 'Talentwise, they don't have the same as last season. (Cristiano) Ronaldo has been a big miss.'
High hopes: Manager Gianfranco Zola
Zola admits that his approach will be to 'out-score' the opposition rather than focus on patching up his leaky defence.
United have lost on two of their last three visits to West Ham and were given a scare last time round before scraping a 1-0 win.
With Ferguson's men already trailing leaders Chelsea by five points, Zola can do his old employers at Stamford Bridge a massive favour. Reflecting on the recent matches between West Ham and United, Zola said: 'West Ham played with a lot of passion, attention and desire - and that overcame the quality of Manchester United. I'm expecting something like that on Saturday.
'Last season we played a tight game. We made one mistake and Ryan Giggs punished us. That was the difference. You need to keep your attention for 90 minutes.'
Cole, West Ham's top scorer with seven goals, will be missing until the New Year at least but Zola thinks Mexican Franco can fill the England striker's boots. Zola said: 'I see it as an opportunity to find other ways to keep the goals coming.
'Franco is very good at holding the ball and very intelligent. We might use him as a target man but maybe get the ball to him in a different way.
'I knew that he was a good player but I didn't expect him to be that good. And he's got the World Cup ahead.'
Zola is not even sure he will be able to call on Cole after January. He said: 'It depends on how he reacts to treatment.
'We have to take it day by day.'
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