Both players have spent time in the treatment room and the Reds have suffered as a result by fading from the race for a Champions League place.
West Ham travel to Anfield tonight (Monday) knowing that Torres is out for the campaign after a knee operation and Zola offers a simple explanation for Liverpool's problems this season.
Big guns: Torres (left) with Liverpool captain Gerrard
'Gerrard and Torres are massive players, when they are on the pitch it makes a big difference to Liverpool,' he said. 'It's a pity they haven't been available for the whole season because of injuries and Liverpool's problems lie within that.
'Liverpool don't have the same number of players as Manchester United, Manchester City or Chelsea.
'When they are in good form they can be a really good team. They can stand with United and Chelsea. But Torres has had too many injuries and it's a big ask for them without him.'
Tough task: Zola heads to Anfield
Zola insists Liverpool, who are scheduled to play the first leg of their Europa League semi-final against Atletico Madrid on Thursday, remain dangerous even without Torres.
'Liverpool can still cause us problems. Torres is a big asset but I like David Ngog, he can be a problem for us,' he said.
'We don't have to think about Torres' injury being an advantage for us, we still need to perform and do very well.'
A wave of optimism has swept through Upton Park since four points were secured in the last two matches against Everton and Sunderland.
And Zola credits a desire to roll up the sleeves for the change in fortunes.
'The last few games haven't been pretty but the work rate and desire has been top class and that's why we will get important points,' he added.
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