The Soweto giants will be away to the Clever Boys in a PSL match at Moses Mabhida Stadium on Saturday.
Mabasa, whose brace inspired Bucs to a 2-1 league win over Chippa United last weekend, is anticipating a tough match against the Clever Boys.
"It’s a very big match and an important one as well," Mabasa said on Pirates' official site on Friday.
"They say if you want to be the best then you have to beat the best and Wits certainly falls into that category of one of the best teams in the league."
Wits have started the season well by accumulating nine points from their first four league matches as they look to challenge for this season's PSL title.
Mabasa feels it is important to test themselves against the 2016/17 PSL champions after Pirates ended their six-match winless run across all competitions.
"This will be a great test for us to gauge how much we have improved as a team," he continued.
"The fact that we are playing at Moses Mabhida Stadium obviously changes things because it’s a completely different venue from Bidvest Stadium so obviously there has to be slight adjustments in approach.
"The coaches have given us a game plan that we’ve been working on all week and it will be up to us as a team to implement that strategy come the game."
Johannesburg-based side Wits will host Pirates at Moses Mabhida Stadium as their home ground, Bidvest Stadium is undergoing renovations.