The Brazilians are in Group A where they will face South Korean side Ulsan HD, Germany's Borussia Dortmund, and Brazilian team Fluminense.
The two top clubs from the group will advance to the knockout rounds.
Sundowns head into the game having most recently lost to Egyptian side Pyramids over two legs in the final of the CAF Champions League final.
Speaking ahead of their tournament opener against Ulsan at the Inter & Co Stadium next Wednesday, Williams said that Sundowns won't change their style for their international opponents.
He said in the Citizen: "We just have to be ourselves, play our football and stick to our identity because we don't want to go out there and start changing things and playing a different way because of the strength of our opposition.
"We want to play our football because we believe that we have enough to get out of the group. To get out of the group would be positive and it will also be massive for us.
"When you look at our group, there are some big names there and it will be tough but we believe that we can get out of it. We will show people who Mamelodi Sundowns are and what I saw at training is wonderful."
Williams added: "In a perfect world, it would have been great for us to wrap up the champions league and lift the trophy and go to the world cup as continental champions but obviously, it would've given us confidence but now we need to dig deep."
Bayern Munich are on a mission to sign a top-tier attacker following Leroy Sane's unexpected free transfer to Galatasaray, with board member for sport Max Eberl vowing to land an "outstanding player" to ignite their frontline.
Leroy Sane, the dynamic German winger, will don Bayern Munich's colours for their Club World Cup group stage campaign in the United States, despite sealing a high-profile move to Galatasaray.
Percy Tau has confirmed that he is open to offers from all PSL clubs - not just the so-called "big three" of Kaizer Chiefs, Orlando Pirates, or his former side, Mamelodi Sundowns.
Manchester City have confirmed their 27-man squad for the upcoming FIFA Club World Cup, with Jack Grealish a notable omission.
