The Pretoria club have 52 points from 26 matches and need seven more from four fixtures to give them an unassailable lead over second-place Orlando Pirates.
Sundowns coach Pitso Mosimane has repeatedly hailed short, slightly-built Tau during the league season, calling him the South African ‘Messi’.
Tau has reportedly been watched by French Ligue 1 club Monaco after mid-season moves for him by Danish and Russian sides fell through.
The 23-year-old favourite to be crowned South African Footballer of the Season set up Themba Zwane and Sibusiso Vilakazi to score during the opening half in Pretoria.
Tau is also in contention for the Premiership Golden Boot award as he shares first place on 11 goals with Rodney Ramagalela from lowly Polokwane City.
“We are getting there,” Mosimane said as his team edged closer to a record-extending eighth Premiership title for a club bankrolled by mining magnate Patrice Motsepe.
“We dominated the first half but were guilty of over-elaboration at times, making too many passes instead of shooting.
“I liked the way we managed the match in the second half, making sure Wits did not get back into it.
“Wits relied a lot on crosses and we were prepared for that tactic and handled the situation impressively.”
Wits dropped to 11th, one season after becoming South African champions for the first time since the Johannesburg club was formed in 1921.
“We are capable of playing much better than we did tonight,” said coach Gavin Hunt, who won three consecutive Premiership titles with SuperSport United before joining Wits.
A loss of form by fifth-place Free State Stars continued as they could only draw 1-1 at home to Bloemfontein Celtic in central town Bethlehem.
Goodman Dlamini put Stars ahead four minutes into the second half only for Victor Letsoalo to equalise soon after.
SuperSport, one of the pre-season title favourites, remain precariously placed just above the danger zone after drawing 0-0 at Cape Town City.
Second-from-bottom Ajax Cape Town trail United by two points and can climb above them Sunday with a win at Chippa United.
Impressive City attacker Craig Martin came closest to ending the stalemate by hitting the post midway through the first half.
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