The Cottagers must now find common ground with Trabzonspor themselves, with the Turkish club demanding a minimum of €30m before they will sanction the Nigeria international's departure.
Nwaiwu, 22, took Turkish football by storm last season. Signed from Austrian side Wolfsberger AC for €6m in January, he swiftly nailed down a starting spot at the heart of the Trabzonspor defence, featuring 21 times as the club sealed a third-place finish and a return to European competition.
His performances did not go unnoticed at international level either, earning him a first Nigeria call-up, and he now has three caps for the Super Eagles. He also found the net three times over the course of the campaign, underlining the threat he carries in the opposition box.
Trabzonspor's asking price reflects just how quickly the defender's stock has risen. A sale at €30m would hand them a profit of around €24m on a player they signed barely six months ago, and would go down as one of the biggest deals in the club's history.
Fulham's persistence in the chase suggests they are far from deterred. The west London club have reportedly seen two earlier bids knocked back, an opening €20m offer followed by an improved €28m package, but with personal terms now in place they believe the deal can be pushed over the line.
Nwaiwu has emerged as the priority defensive target of Fulham's summer as new head coach Alvaro Arbeloa begins to shape his squad following his appointment earlier this month. Should the move be completed, the defender would link up with Nigeria team-mates Calvin Bassey and Alex Iwobi at Craven Cottage.
For now, all eyes turn to the negotiating table. Fulham are edging closer to their man, but Trabzonspor have shown no inclination to soften their stance, and the coming days should reveal whether the Premier League side are prepared to meet the €30m price.