The White Hart Lane boss saw his team fail to make up crucial ground on Saturday when Spurs dropped more points against West Ham in a goalless draw.
Tottenham have now taken just two points from a possible nine and have lost their grip on fourth place.
Nailbiter: Redknapp (left) and Roberto Mancini will battle it out for fourth spot
Even if they win their game in hand over City, Spurs will fail to overhaul their main rivals for the final Champions League position.
Redknapp said: 'Most people's money would be on Manchester City. They are the favourites and they should be. I think the Tottenham squad is not really big in comparison to a lot of others.'
Spurs edged out City for fourth spot on the final day of last season and Redknapp reckons it will be another nailbiter in May.
He added: 'We've done a tremendous balancing act all season with domestic competitions and playing in the Champions League, we've stayed there all year.
'Playing so many games week in week out does take its toll and you end up paying for it with either injuries or fatigue.
'One time this season I was so short of senior players I named two goalkeepers on the bench at Blackburn.
'Tottenham have been in the top four or five all year. It's not easy, it's tough fighting on two fronts.
'If we carry on our run in the Champions League, it will mean playing Saturday-Wednesday, Saturday-Wednesday.'
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