The Gorgie head coach anticipates a bounce factor from Wednesday’s appointment of former United striker Mixu Paatelainen as manager.
The Finn replaced Jackie McNamara and Neilson believes he will have an immediate impact on a side that sit bottom of the Ladbrokes Premiership with five points from ten games.
He said: “I think it is a good appointment. Mixu has had a good managerial career It is a different game now. It is a different Dundee United we will be playing against.
“I am sure since Mixu has taken over there has been a lot of energy in training.
“It is a clean slate for every player. The guys who haven’t been in the picture now have a chance to get in the team.
“They will be desperate to impress, desperate to perform, so we need to make sure we go up there and are ready for it.
“It will make it an intriguing game.”
The promoted Jambos have not won in five league games but remain in third place in the table, which Neilson describes as more than satisfactory.
“I am delighted with the position we are sitting in,” the former Hearts defender said. “If we get a result in the United game, we will be sitting in third position.
“For a team that has been promoted in the summer, it is great.
“We had a great start. It has been a wee bit difficult recently but the performances have still been there.
“In the last few games we have created a lot of chances but didn’t take them, but at least we are creating.”
Neilson declined to explain the departure of under-20 coach Jack Ross, which was announced via the club’s official website earlier week.
He said: “The club has put out a statement and that is all we want to talk about on that.
“The focus is on Sunday and we move on. It is a club decision.” Asked about a replacement for Ross, the Gorgie boss said: “It has only happened recently so it is something that will be looked at.
“At the moment, myself, Stevie [Crawford], Liam Fox and John Hill, the sports scientist, are all helping out and getting things covered but the club has put out a statement and that’s where we are at the moment.
“Any under-20s role at any club is something you have to look at because it is important.
“I enjoyed my time at it and there will be a lot of people interested in it, but it is up to the club to decide what they do.”