Hailee Steinfeld accompanied Niall Horan to the US Masters golf tournament.

Niall Horan

Niall Horan

The 'Pitch Perfect' actress has been romantically linked to the 'Slow Hands' hitmaker for some time, and it seems the 24-year-old singer is thinking seriously about the 21-year-old star as he invited her to join him in watching his favourite sport earlier this month.

According to the Mail on Sunday newspaper, Hailee, Niall, and his professional player friend Thomas Bjorn all shared a house in Augusta, Georgia, during the four-day event.

The news comes a few weeks after it was revealed the pair are "casually dating".

A source said recently: "It's true that Hailee and Niall are dating, but at this point it's still pretty casual."

In February, the couple enjoyed a weekend in Las Vegas, where they went to see Backstreet Boys perform at Planet Hollywood Resort and Casino before taking a stage table at XS Nightclub during a DJ set from Diplo.

Meanwhile, Niall will be able to give Hailee further lessons in his favourite sport as the former One Direction star - who has his own Modest! Golf management company to help scout new talent - recently had a golf room installed in his house.

The singer recently took to Twitter to show off the room, which has been decked out as a mini golfing green, complete with a hole and an outer rim of fake grass.

He captioned the snap: "thank you @prolawnturf and @celebrity greens for sorting me out with this room . (sic)"

Whilst it is likely Niall's new room will be used for him to indulge in his hobby, he may also use the mini green to hone his skills.

The 'This Town' singer previously revealed that he plays with a handicap of nine, and would never consider swapping his music career for a life as a professional golfer, as he doesn't think he has the natural skill required.

He said: "I'm a sports fan in general and I watch a lot of sport and when I was 12 or 13 I joined my local golf club and fell in love with golf then. I play off 9, it basically means I'm not as good as the pros, if I wanted to be a pro I'd have to be plus 5 or 6 so I'm quite far away from that. If I had natural talent for golf then I would go pro. I'm a plodder and a hacker, like all the other amateurs. I'm even worse at mini golf!"