The Brazilians top the league standings with 39 points from 14 games, but the Buccaneers are hot on their heels with 33 points from 13 matches played.
The two teams have been fighting on a number of fronts this season, and both teams are into the knockout rounds of the CAF Champions League and last 16 of the Nedbank Cup.
Pirates, meanwhile, scooped the MTN8 with a 3-1 win over Stellenbosch in the final, with Sundowns having lost 1-0 to the Cape Winelands club in the semi-finals.
While Downs last beat SuperSport United 3-0 in the league, Pirates overcame 2-1 to Sekhukhune United.
Ahead of the weekend's game, the Downs captain said in the Citizen: "Both teams have been doing well and we know these games are won on small margins.
"If you look at the last few games we've played against them, there hasn't been a high score but the football has been of the highest quality."
In this fixture last season, Sundowns edged Pirates 1-0 at Orlando Stadium ahead of a 1-1 draw at Loftus.
"It's two powerhouses of South African football and in Africa that are doing well so it’s going to be a good game," added Williams.
"I know that this is the game that everyone has been looking forward to and I think it has come at a perfect time for both teams because we're playing a good quality brand of football. When we have to grind out results, both teams know how to do that as well.
"For us, the most important thing is three points because they will take us nine points ahead of them. As much as they're bragging rights, for us three points are the most important thing and we're looking forward to doing that at home."