Leeds United v Newcastle United Football has a funny way of working itself out.
But medial cruciate ligament knee injuries in both games – one for Ethan Ampadu, one for Ao Tanaka – mean the 27-year-old's first league start for his new club could well come against his beloved Newcastle United in the televised Saturday evening game (5.30pm kick-off).
Longstaff is a victim of modern football culture, where academy players are reared to be sold for profit and sustainability purposes, and where super-rich clubs are always looking for the next big thing.
From the local hero of a cut-price Magpies team, Longstaff found himself competing for a place with Bruno Guimares and Sandro Tonali in a Saudi super-charged midfield. No wonder he only managed eight Premier League starts last season.
More – if not quite so high-quality – competition at Leeds and the rustiness which comes with too much time on the St James' Park sidelines is why Longstaff was only a substitute against Everton and Arsenal.
Leeds are yet to see the best of the midfielder – only highlights – and according to manager Daniel Farke, it might be a while yet before they do. It was his penalty Sheffield Wednesday's Ethan Horvath saved to knock Leeds out of the League Cup on Tuesday, on a night where Longstaff at times struggled to bottle his frustration.
Passion will be in play again when he takes on Newcastle, but Farke says there is much more to the £12m signing's game than just that.
MIXED BAG: Sean Longstaff is still searching for rhythm at Leeds United (Image: Michael Regan/Getty Images)placeholder image
MIXED BAG: Sean Longstaff is still searching for rhythm at Leeds United (Image: Michael Regan/Getty Images)
"He’s intelligent – a top character – and we’re pretty pleased to have him here," says his new manager.
"He’s a great team-mate to the rest of the players and it’s a joy to work with him every day.”
But there is a but – an understandable one.
"I think it’s fair to say that you could feel in the first few weeks of pre-season that he didn’t come here with full confidence and full rhythm,” says Farke.
CHAMPIONS LEAGUE HIGHLIGHTS: Sean Longstaff celebrates for Newcastle United against Paris Saint-Germain in 2023 (Image: Stu Forster/Getty Images)placeholder image
CHAMPIONS LEAGUE HIGHLIGHTS: Sean Longstaff celebrates for Newcastle United against Paris Saint-Germain in 2023 (Image: Stu Forster/Getty Images)
"That’s due to the fact that he’s not played as much in the past season as he has in the years before because of the competition in his position.
"He’s still on the way to finding his rhythm so I don’t think we have seen the best Sean Longstaff so far.
"He had some really good games in pre-season but also some when he perhaps wasn’t at the top of his game. This is normal for a player who doesn’t come with full confidence and full rhythm.
"This will just come in time.
SUPPORT: Daniel Farke has been impressed by Sean Longstaff's character since he joined Leeds United (Image: Julian Finney/Getty Images)placeholder image
SUPPORT: Daniel Farke has been impressed by Sean Longstaff's character since he joined Leeds United (Image: Julian Finney/Getty Images)
"It’s the same with Dominic Calvert-Lewin. It feels like Sean is growing day by day and it was also important for him to have 90 minutes in a competitive game under his belt in the Carabao Cup (Calvert-Lewin came off the bench).
"There is space for improvement, there’s no doubt about it.
"But I’m pretty sure due to his character and his mentality – he always works at his game – he will be able to reach his best level again and then we have a really good player."
Longstaff is the son of former Sheffield Steelers and Great Britain ice hockey winger David, but was born and bred in the north east, where his dad played for Newcastle Vipers and Whitley Warriors, who he later coached.
He and brother Matty lived the dream of so many in the area, wearing the famous black-and-white stripes for seven seasons, even scoring in the Champions League past Paris Saint-Germain goalkeeper Gianluigi Donnarumma. Kylian Mbappe was unable to find the net for the visitors, who lost 4-1.
"I’m sure it will be an emotional day for Sean due to spending the last 20 years at Newcastle," says Farke. "But he’s wearing a Leeds United shirt now and fully committed to this club – you can feel it.
"He’s fully integrated and he loves being here and being a part of our group. I have no doubt that he’s highly motivated and will be very professional to put his past to the side and focus on digging in and trying to grind out a result for us on Saturday."
The Newcastle team could feature Nick Woltemade – if not the striker to replace the wantaway Alexander Isak, then a striker to replace him – but are without the suspended Anthony Gordon and have injury concerns over Joelinton and Sandro Tonali.
It feels like an evening where the narrative could go either way.
A Leeds victory would bury the hammering at Arsenal and the no-show in Sheffield, and build a storyline about fortress Elland Road by adding the scalp of a Champions League team to that of Everton.
A good end to the transfer window, with Leeds' focus seemingly on a "No 10-type" winger with Sheffield United's Gustavo Hamer starting to look more gettable than Chelsea target Facundo Buonanotte, would only continue the feel-good vibes.
But if a Newcastle team who played so well in defeat to Liverpool on Monday can be buoyed to victory by Woltemade's presence, Leeds' last two setbacks cannot be brushed off quite so easily.
It promises to be an important night for the men in white. Leeds need to see as much of the really good stuff as possible from Longstaff.