"We're playing at their home ground so they have a chance. I'm giving them 50-50," Neeskens told reporters on Tuesday.
"We're playing a Premiership team, so we know each other and I hope it will be an entertaining match."
He brushed aside any expectations that their record 24-0 win over amateurs Powerlines FC in the previous round would result in another high-scoring game.
"I think that is a joke. It's impossible that we will beat Wits by the same margin," Neeskens said sternly.
"We don't care if it's one goal that's the difference, the intention is to go through to the next round.
Wits, who were finalists in the Telkom Knockout in December, beat high-flying Moroka Swallows 1-0 in the last 32.
While they come off two league losses, coach Roger de Sa's exciting Clever Boys will be charged up for the tie against the Brazilians.
"Wits have just had two losses, but they will be up for the challenge," Neeskens said.
Sundowns have set their sights on lifting the league trophy and this cup – the South African version of the FA Cup – this season.
While the championship is still a higher honour for Neeskens, with nine games remaining, equally, the cup had a place in the side's Chloorkop headquarters.
"The cup is not a distraction for us," said the coach.
"All teams try to win as much as possible, so I'm definitely looking forward to this (cup) as well."
Sundowns report no injuries to their formidable squad.
The outfit would have played three games in eight days after the Wits encounter.