"I think we’ve seen in recent times with Liverpool that Fenway Sports Group have had no hesitation about putting serious money on the table to solve problem areas or improve upon what they’ve got in areas of the team," Castles told the Transfer Window Podcast.
"And they’ve gone for top targets at high prices, like Virgil Van Dijk, Naby Keita, they’re working at the end of the transfer market where you can identify a player that fits your system and you have the money, unless one of the other really big clubs come in against them, to make those deals happen.
"In fact, you can say even when one of the big clubs come in against them, because Virgil Van Dijk was of serious interest to Manchester City last January and they basically stepped away because of the offer that was on the table in terms of salary and transfer fee from Liverpool for Van Dijk.
Jurgen Klopp could have the resources to spend big in January (Image: GETTY)
Philippe Coutinho's sale to Barcelona has given the Liverpool owners confidence to spend (Image: GETTY)
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"It would not surprise me if FSG did the same in January, because they’re prepared to go there and they’ve got a lot of faith in Jurgen Klopp and they’ve got a lot of faith in their recruitment department.
"That's because they’ve had a series of successes and made big profits on a couple of players, Luis Suarez and Philippe Coutinho in particular, which gives them the financial argument that it’s worthwhile spending heavily on players as these guys they get value from."
Express Sport understand one of those targets could be Brighton assist king Pascal Gross.
Virgil van Dijk has proven to be a successful spend of Liverpool's transfer budget (Image: GETTY)
Klopp is considering a £15million move for the 27-year-old German in January.
Gross was Brighton's player of the year last season after scoring seven goals and making eight more following a bargain £3m move from Ingolstadt.
Klopp believes freekick specialist Gross would be a cheaper alternative to Lyon ace Nabil Fekir.
The Anfield chief spoke of his admiration for Gross, who he watched when he was managing Borussia Dortmund in the Bundesliga, last year. He said: "He has a nice right foot and is good at set-pieces. He is a smart player and I like him."