'I asked the lads at half-time to add some more passing to our game and not be so one- dimensional,' said the new Bolton manager.
It worked. Within three minutes of the restart, Gretar Steinsson had given Bolton the lead and Johan Elmander added a second to put them into the fifth round.
1-0: Gretar Steinsson hails the Reebok faithful after putting Bolton a goal up
Sheffield United manager Kevin Blackwell was not impressed. He said: 'Two sloppy goals, make no mistake about it. There was nothing in the teams. It would be hard to tell which was the Premier League side.'
Blackwell is looking for a centre half, having sold Matt Kilgallon to Sunderland and seeing Marcel Seip pull a hamstring in the pre-match warm-up.
There was discontent in the stands as mistake followed mistake in the first half, with Bolton the biggest culprits as the workmanlike visitors harried their opponents.
At full stretch: Gary Cahill vies with Henri Camara
United should have scored first. Henri Camara was through with plenty of time to lob the advancing goalkeeper, Jussi Jaaskelainen, but his lob sailed over.
Bolton led when Kevin Davies slipped the ball wide to Steinsson, who shot home from the narrowest of angles.
Old pals' act: Kevin Blackwell and Owen Coyle - who met in last season's play-off final - share a joke on the sidelines
Minutes after Coyle had taken off Ivan Klasnic his replacement, Elmander, ensured Bolton's passage.
Chung-Yong Lee lifted the ball cleverly over a defender and Elmander ran on to it to score from an angle not quite as acute as Steinsson's.
Bolton boss Coyle tones down 'assault' claim on Arsenal defender GallasCoyle's Bolton bust-up with No 1 Jaaskelainen over goalkeeping coachBOLTON WANDERERS FC