Australia great Viduka, 44, was uncharacteristically open in an interview with ESPN, discussing the Socceroos captaincy, issues within the squad, and the disappointing 2007 AFC Asian Cup campaign.
After the high of the 2006 FIFA World Cup, the Socceroos were one of the favourites in their first continental tournament as part of the AFC, but crashed out via penalty shootout against Japan in the quarter-finals.
When asked if he thought his captain had been undermined at that time, Viduka replied "definitely" and singled out centre-back Neill.
"I think Lucas Neill, at that stage, came to that Asian Cup not in a good state of mind because of the fact that [head coach] Graham Arnold had offered him the captaincy - because he wasn’t sure whether I was going to come to the Asian Cup or not," Viduka told ESPN.
“Once I was at the Asian Cup, either he [Arnold] wasn’t brave enough to tell me that I wasn’t captain anymore, or whatever, and I felt that Lucas Neill was sulking that whole Asian Cup. Through the preparations for it and through the Asian Cup, and it affected other players.
“I think Lucas tried to undermine me.
"I think his priority was to be captain — more because of his other activities he had off the pitch rather than actually on the pitch stuff. That’s my opinion.
Viduka also pinpointed the selfishness of younger players as one of the reasons for their poor showing, and said their attitude left him disillusioned.
"I think some people came to that Asian Cup thinking more about themselves more than the national team," he said.
"There's people who value themselves very highly and think more about their television rights and deals and all that than actually playing for their country.
"That was the main reason I stopped playing for the national team.
"My problem was that my generation of players that I grew up with were a different breed to the newer generation, and, to be the honest, I wasn’t a big fan of the newer generation of players.
"A lot of them were more interested in how many deals they were having on the side, through sponsorship and getting their heads on the television, than actually playing for the national team."
Viduka retired from international duty after the tournament, but said he has no issue with Arnold, who is now in charge of the national team once more.
"Hopefully he's learnt a lot from the days of when he coached the national team at the Asian Cup - especially man management," he said.
Talking about Australian football more broadly, Viduka said he thought there was "a big gap in terms of player development" compared to his time in the game, especially since the formation of the A-League, and rued the closure of the FFA Centre of Excellence at the AIS in 2017.
"There's something missing with the player development," he said.
"I think that when they did the A-League, they concentrated more on getting the league set up but this junior system that actually developed players, I don't think they paid enough attention to."
