Drudru was given the marching orders by referee Bertrand Billon in the dying stages after a heavy collision with Angel Berlanga who had to be stretched off the field.
The send-off left Vodafone/Shop N Save Nadi coach Kamal Swamy fuming. Swamy claimed that both players went in hard at each other.
"Some of the decisions were not good," Swamy said.
"In the last incident where Drudru was red-carded, I believe the Auckland City player should have been red-carded as well because he also came with his studs up."
The red card could rule Drudru out of the group stage with a decision yet to be made.
Auckland City FC dominated the first half denying Nadi possession. Strikers Emiliano Tade (Argentina) and Joao Moriera (Portugal) combined well for the Kiwis.
Moriera scored the opener in the 12th minute with a cool finish from inside the box. Daewook Kim scored the second in the 23rd minute after a defensive blunder.
Tade got the third in the 40th minute after being set up by stylish Moriera.
Nadi stepped up in the second spell. Swamy brought on Jone Salauneune for Napolioni Qasevakatini.
The Jetsetters tried hard to breach the Auckland City FC defence but often lost the ball when on attack.
Swamy defended his players saying they were young.
"People should realise that Nadi is playing in the competition after 15 years," he said.
"These are young players and are bound to make mistakes. They were under pressure and made mistakes which Auckland City capitalised on.
"If you look at the match, Auckland City was not able to build anything and score. They scored from the errors that we made.
"If we had worked on those then we would have matched them."
Auckland City FC coach Ramon Tribulietx was happy with the result but expressed disappointment with the injury to Berlanga.
"In terms of football we played a good game," Tribulietx said.
"In the first half we played great football creating a lot of chances. In the second half it was a bit nasty but I suppose that is part of the game. We are happy with the three points but not happy with the injuries sustained.
"We have brought a 20-member squad over. We are not sure of the extent of injury to Angel after that crazy tackle."
Suva (Fiji Times)