With eight games remaining, the Wanderers sit three points behind sixth-placed Western United with a game in hand.
It is remarkable that we are talking about Western Sydney as potential finals contenders after a shocking start to the season, which saw manager Markus Babbel fired after four wins in 14 games.
His replacement, Jean Paul de Marigny, has since revitalised the squad, going unbeaten in four games prior to Friday's loss to Brisbane Roar.
Their opponents this weekend are second-placed City, who defeated them 3-2 at BankWest Stadium in November.
A lot has changed since that game, and Muller is adamant the Wanderers can cause an upset, and eventually sneak into the finals.
He told Tribal Football: "We are in a good way the last five weeks. The Brisbane game was not so good but I think we can beat every team in the league when we get 200 per cent on the park.
"We can make the finals but we have to do everything at 100 per cent. We did a little bit less against Brisbane and we lost.
"When you see the games at the weekend, every team can beat everyone, that's the thing. We need to be looking forward and work hard, then we can go to the finals."
Muller says he would like to have more than five goals this season, a modest return for any attacking midfielder, but possibly not for someone with over 250 appearances across Germany's top two divisions.
It was under three years ago that Muller was a hero at Hamburg SV, keeping the club in the Bundesliga by scoring an extra-time winner against Karlsruher in the 2017 relegation play-off.
Premier League clubs came calling that summer, and the German admits he "had an offer from West Ham", but chose instead to remain in his homeland.
A serious ACL injury would derail Muller's momentum the following season, eventually leading him to seek options away from Germany, where he also played for Eintracht Frankfurt, Mainz and Hannover.
"I had other options in Europe before the transfer deadline day. I was in [Eintracht] Frankfurt and said to my manager that I'll stay here for the next five months in Germany.
"And then Markus called me and said they want me here. I got more information, I talked to Pirmin (Schwegler) because I knew him from Hannover, and then I said to my family, let's go and start a new adventure.
"It was a little bit difficult [to begin with] because the weather and everything is different to Germany, also because we were losing games, it made it harder for me. This was a bad situation.
"But I feel good from the first moment and I'm happy to go to the training every single day, my family loves it here in Sydney and I love it too."