Spezia centre-back Jakub Kiwior was pictured at the Emirates Stadium for Arsenal's Premier League game with Manchester United ahead of his imminent move to North London.
Last week, it was reported that the Gunners had agreed a €25m (£21.9m) deal to sign the 22-year-old, who will join on a five-and-a-half year deal.
Arsenal and Spezia quickly came to an agreement over a transfer fee, and Kiwior flew to England on Saturday in order to undergo his medical ahead and sign his long-term contract.
Kiwior is understood to have completed his medical on Saturday prior to meeting his new teammates, although neither Spezia nor Arsenal have publicly announced an agreement yet.
However, the Poland international was pictured in the Emirates box on Sunday, where he witnessed Arsenal record a thrilling 3-2 win over Man United ahead of his switch.
With Kiwior in attendance, Arsenal were forced to bounce back from an early Marcus Rashford effort, but Eddie Nketiah's header and Bukayo Saka's brilliant curler turned the game on its head.
Lisandro Martinez's header pegged Mikel Arteta's side back again, but Nketiah flicked home a 90th-minute winner to propel the Gunners five points clear of Manchester City at the top of the Premier League table.
Arsenal have now moved onto 50 points from their first 19 matches of the Premier League season and boast a game in hand on Man City, who they meet in next Friday's FA Cup fourth-round showdown.
Kiwior's signing should be announced in the coming days, as the Polish defender arrives at the Emirates to provide cover and competition for Gabriel Magalhaes in the backline.
The left-footed 22-year-old has predominantly featured as a centre-back for Spezia and Poland, but he has also been deployed as a left-back, left-wing back and defensive midfielder at club level.
Kiwior prepares to leave Spezia after making 43 appearances for the Serie A side in all competitions, having joined from MSK Zilina in 2021 for just €2.2m (£1.9m).
The versatile defender has earned eight caps for the Poland national team and started all four of their games at the 2022 World Cup, helping his nation reach the last 16.
Kiwior will become Arsenal's second signing of the winter transfer window following the acquisition of Leandro Trossard, who made his debut off the bench against Man United on Sunday.
The Gunners are being tipped to reinforce their backline further this month with the signing of Real Valladolid's Ivan Fresneda, who is now understood to be in direct talks over a switch to North London.
A new midfielder has also been a priority for Arsenal for a number of months, but the North London giants are expected to wait until the summer before making a move for West Ham United's Declan Rice, who has supposedly been earmarked as their top transfer target.
