Both teams are in the hunt for league honours along with log leaders Cape Town City and SuperSport United.
Downs have 34 points from 17 games - three points shy of City and two less than Chiefs, but with four games in hand.
However, Mosimane insists this is not the right time to take on Amakhosi.
“We are the underdogs at this point in time because Kaizer Chiefs have been better in the league,” Mosimane said at a press conference in Parktown.
“If you can check the last maybe eight games there was a stage that they went five games in a row [unbeaten in the league]; so we envy them and we wish we can do five in a row also.
“And they’ve also drawn three… and we have drawn two and lost one so we not in a very good space at the moment and if I understood 'Shabba' [Siphiwe Tshabalala] well the medical room [of Chiefs] is empty. So that’s [also] one of the things that make us not to be in a good space.
“And lastly obviously the number of games that we come back from and I think they have more fresh legs with less games than us… and obviously because of CAF and also the games that we have to catch-up.”
He added: “So we are not playing them at the right time. It’s not the right time to play them… could have been better at another stage but we have to honour the fixture.”