It’s up front where United have the least amount of options but they do have players in attack in excellent form.
Morgan Gibbs-White and Iliman Ndiaye have been superb of late and the onus will be on them to get the goals United need to take the advantage going into Tuesday’s second leg at the City Ground on Tuesday.
Heckingbottom said earlier in the week: “Bill’s (Sharp) another few days closer. We’d like him to be (able to play), if he's available to play some part in the tie.
"If he’s not ready, he’s not ready. He is doing all he can and the staff are doing all they can to make sure there is that opportunity.”
“Morgan (Gibbs-White) has been back on the grass today (Thursday),” added the Blades boss.
"Conor (Hourihane) and Morgan didn’t train last week.
"We’re fine. George (Baldock) has had more training minutes in him, he’s looking good.
"Touch wood, everything at the minute is as good as it can be.”
Baldock returned to the substitutes bench against the Cottagers having limped off against Bristol City on Easter Monday with a hamstring injury.
5. Jack Robinson
The unexpected hero of the past six weeks or so, Jack Robinson has been excellent in recent games after a tricky period earlier in the season. Becoming more of a forward threat on the left, too Photo: David Klein
6. Enda Stevens
Starting to look a little more like his old self lately. It's been a difficult season for Enda Stevens because of injury but he's coming good at just the right time. He too will have a big task on his hands such is Forest's pace in wide areas Photo: Darren Staples
7. John Fleck
Like Enda Stevens, a season punctuated by injury and illness has made things difficult for John Fleck but he too is coming into good form at a crucial time and should edge out Conor Hourihane for a place in midfield Photo: Simon Bellis
8. Ollie Norwood
Has a huge part to play against Nottingham Forest - everything goes through him when he plays in this slightly deeper role and it will be up to him to get the attacking play started, as well as breaking up the play in the middle. Playing superbly of late. Photo: Andrew Yates