The two frontmen have started the season in blistering form and proved too hot to handle for a lacklustre Blades backline as Athletic dominated the match.
The home side had approached the game as the only unbeaten side in the Coca-Cola Championship and never looked like slipping up against a United team short on confidence after losing their last two league games.
And the Latics took the lead after half an hour when Blades defender Phil Jagielka only managed to clear a Gary Teale cross right into the path of Ellington who rifled in a volley from 25 yards that left Paddy Kenny in the United goal with no chance.
Ellington and Roberts had already earned the praise of Blades manager Neil Warnock, who described them in a pre-match interview as being "as good as anyone in this division."
And he was soon proved right, as the two hitmen combined superbly to put Wigan two up.
This time Ellington turned provider, breaking down the right flank before squaring into the path of Roberts who fired home from six yards.
And the game was all but over less than two minutes later as the Latics moved three in front. Ellington grabbed his second, this time with a brilliant strike from the edge of the area after being set up by midfielder Per Frandsen.
United had started brightly, with Jack Lester a constant menace up-front despite picking up a booking after less than a minute for a foul on Wigan goalkeeper John Filan.
But despite an industrious performance, the Blades struggled to create many clear cut chances.
And despite pulling two goals back at Leicester in midweek when they went three down, they never looked like getting back into the game here as Wigan's midfield dominated things throughout
The Blades tried to respond and Lester was replaced at teenage striking starlet Jonathan Forte who started the second period brightly, soon forcing Wigan defender Ian Breckin into a sharp block with a drive from 18 yards.
But it was not to be as Wigan continued to create the best openings throughout the second half before Roberts slammed in a fourth in injury time.