Only Fernando Torres' goal seven minutes from time prevented an embarrassing Chelsea exit at Griffin Park, where interim manager Rafael Benitez came under fire from his own supporters.
That unhappiness continues and, coupled with a number of other factors, leads goalkeeper Moore to believe Brentford can upset the apple cart.
"Chelsea Football Club at the moment does seem a very strange place," he said.
"Stood in the goal at Griffin Park the other week you could hear them at half-time screaming at their manager, saying they want him out.
"It must be an uncertain time but for us, to be honest, it is probably the best possible time to play them.
"Sunday is going to be a great opportunity for all of us and one that we're very excited about.
"We're going to go into it full of confidence, with every belief we can get through.
"After the first game, we sat in the changing room and were genuinely disappointed. We really felt we could have won the game.
"We've got another chance on Sunday to show what we can do again.
"We're going to go full of belief and we really feel we have a great chance to go through to the next round."
With Brentford in the spotlight once again, it gives Moore another chance to show Southampton what they are missing.
The Premier League club released the goalkeeper when he was still at school, leading him to ply his trade in non-league until a successful trial at Brentford aged 19.
"I was with Southampton as a 13-year-old lad and was over there for a season," Moore said.
"At the end of the season they said I was too small, which basically says 'you're not good enough'.
"At the time I was hugely disappointed and when you're a 13-year-old lad it devastates you.
"I came into professional football late as players tend to go through the scholarships, academies and obviously I had a little bit of a different route, but I wouldn't have changed it.
"I played a lot of non-league games before coming here and I don't think I would be where I am now if that hadn't have happened."
It allowed self-confessed home bird Moore to stay on the Isle of Wight until his late teens.
The goalkeeper represented non-league minnows Brading Town during that period and even the Isle of Wight itself at the 2009 Island Games.
"I'm very, very proud of the Isle of Wight, it was a fantastic place to grow up." said Moore, whose pride is epitomised by his Twitter name, @SiMooreIOW.
"I've got so much family and friends there, so I love to get back there whenever I get the opportunity.
"It is a place I would like to go back to when I'm older, when I've finished my career.
"I was 19 when I moved to the mainland and I think you have to. There is more opportunity over here than there is there."
That move will see Moore line up at Stamford Bridge, where he would be more than happy to face a penalty shootout despite Chelsea's Champions League heroics last year.
"I would take penalties now," he said. "I would feel very confident if it went to a penalty shootout.
"They have got a fantastic goalkeeper there in Petr Cech, who is very dominant figure and that night in Munich was special for him and for Chelsea Football Club. Hopefully, though, it won't be a special Sunday for them."