Watford lost 5-0 that day in what proved to be Walter Mazzarri's last game in charge and Silva said: "We analysed what happened last season and we know, for the last game, there were six centre-backs missing through injury".
City are second to Manchester United on goal difference ahead of the trip to Watford who themselves are in the top four after the opening four games of the season.
"We need him", Guardiola told reporters at his pre-match media conference.
Despite all his brilliance, Sergio Aguero has been injury prone during all of his years at City, having never played 50 games in a season.
City, meanwhile, have slammed in nine goals in their past two games and head to Watford full of confidence.
But Aguero provided only half of City's scoring total.
David Wagner's men thought they had won it when Kachunga rifled home and video replays suggested the effort may have been wrongly disallowed.
The Hornets have looked very hard to beat under Marco Silva this season, and this could be a potential banana-peel for Pep Guardiola's side.
The Argentine became provider for a slightly offside Gabriel Jesus to put Pep Guardiola's side 3 - 0 up at half time. "City deserved the three points, but I think they are strong enough to come here, to create problems, to win the match".
We can see a lot of goals in this game and are backing on more than 2.5 goals as our prediction.
"He was so important last season". Eleven against 10 was much better but sometimes it's not easy to play 11 against 10, and we did it so well.
So far, six different players have contributed their seven goals in Watford's last four matches of this season.
It makes for an embarrassment of riches Silva believes can only bode well. Newcastle made it three league wins a row by beating Stoke 3-1, Leicester and Huddersfield drew 1-1, and West Brom and West Ham played out a goalless draw.
If the Hornets secure all three points, they would be at the summit of English football's top flight for the first time since 1982.