The Blades arrive in south London on the back of a run of one win in nine games and languishing a point and a place above the relegation zone.
Millwall picked up a battling point from their home game against Norwich on Tuesday night, and victory against United could lift them into the top half.
"They're a big club and I'm looking forward to the game," said Jackett.
"If we can win on Saturday it will make the point against Norwich look good. I told the players this week that four points out of six is our aim."
Source: PA
Source: PA