The Blades saw their lead over third-placed Boro cut to seven points in midweek but still have a better goal difference and a game in hand over Michael Carrick’s men.
Ahead of the game United have some injury concerns, with Billy Sharp ruled out with an ankle issue. So we tasked our man to step into Heckingbottom’s shoes and select the side he would send out at The Den. Here’s what he came up with ...
9. Tommy Doyle
United’s selections get a little more difficult the further up the pitch you go. Sander Berge doesn't look quite at full tilt for me and would be a brilliant weapon from the bench if needed. Doyle anchoring the midfield also gives United more solidity and allows his City teammate to (hopefully) run riot against Millwall Photo: Andrew Yates
10. James McAtee
With Norwood and Doyle behind him, McAtee has more licence to go and roam free and make things happen in my side - and perhaps come up with the moment of magic that may be needed against a dangerous side at home Photo: Lexy Ilsley
11. Iliman Ndiaye
Backed by his manager in midweek to rediscover his scoring touch after netting once in his last 15 games, Ndiaye is still amongst the first names on the teamsheet whilever he is fit - because he still offers such a threat Photo: Lexy Ilsley
12. Oli McBurnie
Now United's top goalscorer this season with 12, it seems a no-brainer to start him at Millwall with Daniel Jebbison providing support later in the game from the bench Photo: Andrew Yates