With Kenilworth Road preparing to host one of the biggest matches in their history against United in the Premier League, there were plenty of stars out on show.
And despite big names like Marcus Rashford, Bruno Fernandes and Harry Maguire arriving at the 11,500-seat stadium, one star outshone them all.
That is because former One Direction member Styles was in the building, even making his way into the Sky Sports studio.
Waiting to greet him was former Liverpool star Jamie Redknapp and United legend Gary Neville, who could not wait to take their picture with him.
Presenter Dave Jones was spotted deep in conversation with Styles, as well as Luton Town defender Tom Lockyer, who suffered a cardiac arrest earlier this season and during their play-off final win over Coventry City last term.
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Styles is an avid United supporter and is in attendance to cheer on the Red Devils.
However, why the three-time Grammy winner was in Luton, remains to be seen.
Styles owns a home in north London, which is somewhat nearby, while the 30-year-old splits his time usually between the United Kingdom and the USA.
The 'As It Was' singer grew up with former United, Real Madrid and Paris Saint-Germain star David Beckham as his hero.
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"I think he was everybody's idol when I was growing up," Harry told OK! Magazine.
"When people asked you that question you almost needed a back-up answer because everyone would say David Beckham.
"We actually met once when we were performing in LA," Harry recalled. "He brought his kids to our concert. He's a really nice guy."