Brighton & Hove Albion head coach Fabian Hurzeler has confirmed that new signing Matt O'Riley will undergo ankle surgery after suffering a "bad" injury on his debut for the club.

The 23-year-old was unveiled as a new Seagulls player on Monday, joining the Premier League club from Scottish giants Celtic for a fee which could rise to £30m.

To the surprise of some, O'Riley was immediately thrown into Hurzeler's starting lineup for Tuesday's 4-0 home victory over Crawley Town in the EFL Cup second round.

However, the midfielder was forced off less than 10 minutes into his debut after being on the receiving end of a late, crunching tackle from Crawley captain Jay Williams, who was not booked for the incident.

Hurzeler was enraged by the challenge, which he felt warranted a straight red card, and stated after the match that O'Riley's injury "doesn't look good".

The 31-year-old Brighton boss has since issued an update on O'Riley's fitness, confirming that he requires surgery, although there is currently no timeframe on his potential return.

O'Riley "very disappointed" but "will come back stronger"

Speaking at a press conference on Thursday ahead of Brighton's Premier League trip to Arsenal on Saturday, Hurzeler said: "Like we expected, it's a bad injury. He needs surgery on his ankle.

"I can't say how long we expect him to be out. We have to look at how the rehab will go but of course it is a tough one for us.

"We will try to support him the best way we can and get him back on the pitch as fast as possible. Let's hope he will be back soon."

Hurzeler added: "I had a small chat with him yesterday. It's not the best situation and he is very, very disappointed but he has good character and he is a very positive guy.

"He looks immediately to the future and says he will be back soon and he will come back stronger. That's a very positive thing.

"I like his attitude. It is very important that you also stay mentally strong in tough moments like this. You can't change it in the end and I think he will come back strong."

Could Gilmour stay at Brighton after O'Riley injury?

O'Riley has joined Brighton after ending the 2023-24 campaign as Celtic's Player of the Year and joint-top scorer, netting 19 goals and registering 18 assists in 49 appearances.

The injury sustained by the Denmark international could force Brighton to keep hold of midfielder Billy Gilmour, who has been heavily linked with a move to Napoli, although Hurzeler was coy on such rumours.

Discussing Gilmour's future, the German said: "All the decisions we discuss together internally with Tony [Bloom], Paul [Barber] and David [Weir]. We do them together and we discuss sometimes of course but there are always arguments for both sides.

"We will decide what's best for the club and then we will make the decisions and the public will see."

Gilmour impressed for Brighton in last weekend's 2-1 Premier League win over Manchester United, but he was not named in the matchday squad for Tuesday's EFL Cup win against Crawley.