Wagner, of course, is a long-time friend and former Borussia Dortmund colleague of Liverpool chief Jurgen Klopp, whose side are fourth.
Jose Mourinho’s United are seventh, three points behind Klopp’s men, who are seeking a fifth successive league win.
But United have won their last four league meetings with Liverpool.
Since Klopp was appointed as Liverpool boss in October 2015, they have scored a league-high 73 goals.
And they have the highest average possession figure of 58.8 per cent.
Klopp has lost just one of his five meetings with former Chelsea chief Mourinho, winning three and drawing one.
Wagner also watched Town’s Under 23 team in Professional Development League action against Sheffield United at PPG Canalside this afternoon.