The two clubs have been negotiating for weeks over a fee, and talks have now reached an advanced stage with a package worth around €10m (£8.6m) on the table - well below the buy-option figure originally attached to last season's loan, which Hamburg chose not to trigger in favour of holding out for a cheaper deal. With the transfer window closing on Tuesday, expectation inside Emirates Stadium is that terms will finally be settled.
It caps a turbulent few years for the Portuguese midfielder since his £34m arrival from Porto in 2022. Vieira made 47 appearances across three seasons at Arsenal but was handed a Premier League start on only five occasions, eventually sent back to Porto on loan in 2024-25 before Hamburg took a chance on him last summer.
That gamble paid off: Vieira scored seven goals in 29 Bundesliga appearances as Hamburg settled back into top-flight football, finishing the campaign as one of the club's most productive attacking players and convincing both parties a longer-term arrangement made sense.
Reaching a fee both clubs could accept proved the sticking point. Hamburg's transfer record sits well below the figure Arsenal originally wanted, and it has taken months of talks - and Arsenal's own growing willingness to cut ties with a player who never established himself in north London - to bridge that gap.
With Arsenal keen to clear space and reduce the wage bill before deadline day, and Hamburg equally determined not to lose a player who has become important to their season, a compromise in the region of €10m looks to have finally broken the deadlock.
Vieira's re-emergence in Germany came after a difficult start to the loan spell, including two red cards in his opening five appearances, before he settled into the role of creative focal point for a promoted side.
That turnaround is precisely why Hamburg have been so determined to make the move permanent, and for Arsenal, the sale marks a quiet but pragmatic conclusion to a signing that, on paper, once promised far more than it delivered.