Amakhosi host the reigning Betway Premiership champions at the iconic FNB Stadium, where ticket allocation has been increased from an initial sold-out 60 000 to 75 000 due to high demand.
With Chiefs having enjoyed a perfect start to the season, winning all three of their opening matches, Mdunyelwa believes momentum, combined with a vocal home crowd, will make the contest even tougher for The Brazilians.
"Playing against Kaizer Chiefs is never an easy game, especially playing at their home venue – they utilise that very well, their crowd is going to come out in numbers and they will have the support," said Mdunyelwa.
"It's very important for us not to dwell a lot on things that have happened in the past, but focus on what we can do in the future.
"We believe if we nullify what they're going to be doing on Wednesday, we stand a better chance of winning, and obviously if our supporters come out in number and give us the 12th man, we can come through because we are the defending champions of the title."
The former Chippa United defender also conceded that the Sundowns camp is still feeling the effects of missing out on another cup final.
"It really pains us because we really want to be in the final because we believe, as Mamelodi Sundowns, we want to be part of each and every final in the country and on the continent," he added.
"We want to play those finals because we have the best team, the best squad, and we want to compete, and it really hurt our feelings as players, supporters and families, who know the sacrifices we put to be in those stages and perform.
"And seeing all that just vanishing in one moment, it kind of hurts because we were really building and expecting to be in the final."