Jack O'Connell and Kieron Freeman scored in either half as Sheffield United extended their lead at the top of League One to seven points with a 2-0 victory over Millwall.
O'Connell struck in the 16th minute, finding the net with a header after meeting a John Fleck cross.
Paul Coutts went close to adding a second soon after when his drive was tipped over by goalkeeper Jordan Archer.
There was a change in goal for Millwall in the 26th minute when the injured Archer was taken off after receiving treatment and replaced by Tom King.
United striker James Hanson then headed wide from a Fleck cross.
Early in the second half, a free-kick from Millwall's Jed Wallace was comfortably saved by Simon Moore.
Freeman then increased the home side's lead after 55 minutes with a low finish from inside the area.
As Millwall looked for a way back, Ben Thompson had a long-range effort saved by Moore and Lee Gregory headed over.
Gregory also shot wide after being put through by Wallace as Millwall failed to get on the scoresheet.