Arsenal's search for a new central midfielder looked to be heading in failure after a move for Lyon's Houssem Aouar stalled ahead of deadline day.
The Gunners desperately wanted a new player to bolster their options in the middle of the park, with Aouar seen as the perfect player to inject some much-needed creativity.
Mikel Arteta also wanted a dynamic player to stiffen the spine of his side, alongside Granit Xhaka and Dani Ceballos.
The number one target was Thomas Partey, who was originally targeted during Unai Emery's tenure.
The 27-year-old has established himself as a key player for Diego Simeone's Atletico Madrid in recent seasons, and shone in the La Liga side's run to the Champions League quarter-final in August.
Partey's standout display was in the 1-0 win over Liverpool in the round of 16 first leg before the season was interrupted by the COVID19 pandemic.
The midfielder showed exactly why Atletico were so keen to tie him down to a new contract at the club, and why his dramatic departure to Arsenal on deadline day was greeted with frustration.
Against the Premier League champions, Partey was utterly dominant in midfield against Fabinho, Georginio Wijnaldum and Jordan Henderson.
The Ghanaian won 13 of his 19 duels, completed 13 recoveries, five of which were in his own half and completed five interceptions.
The midfielder also won 100% of all three aerial duels he competed in.
Of Partey's 34 passes during the game, 27 of them were accurate.
The midfielder was the linchpin that kept a formidable Liverpool attack consisting of Sadio Mane, Mohamed Salah and Roberto Firmino quiet, with the Reds failing to have a single shot on target throughout the game at the Wanda Metropolitano.
The damage was done, and Atletico sealed their passage to the next round with a second leg victory at Anfield three weeks later.
Arsenal have had their fair share of struggles defensively in recent times, with Arteta switching to a back three to compensate.
The summer arrival of Gabriel Magalhaes has added further strength in depth at the back, but Partey's introduction in front of the defence could make all the difference.
Arteta said following Partey's arrival: "We have been watching Thomas for a while, so we're now delighted to add such a high quality player to our squad.
"He is a dynamic midfielder with great energy. He brings a lot of experience from a top club that has competed at the highest level in LaLiga and the Champions League for several years.
"We're very impressed with his attitude and his approach to the game. He's an intelligent footballer and we're looking forward to him integrating into our system and contributing to the progress we're building at the moment at the club."
Partey has already proven himself against the best the Premier League has to offer.
Arsenal may finally have the transformative signing they need to mount a serious top four challenge.
