With a number of transfers having already been confirmed in this window, here are the most surprising deals that have gone through so far, including a 2018 Fifa World Cup winner's shock move to Spain.
Click through the gallery above to see some transfers in this window that took many by surprise.
Last season, Liverpool looked set to sign France international Nabil Fekir, who also had other European giants chasing his signature.
The 26-year-old was also a part of his country's 2018 World Cup-winning team in Russia, although his role was mainly as a substitute from the bench.
In a move that caught many off-guard, Fekir has become Real Betis' latest signing, and for a reported fee of just €19.75 million (R306 million). Included in the deal was his brother Yassin Fekir, who also joined Betis from Olympique Lyon.
Staying with LaLiga, Kieran Trippier's switch from Tottenham Hotspur to Atletico Madrid seemed to leave many dumfounded, especially as the only potential destination that had been discussed before his move was to Serie A.
The England international will form part of a new-look Los Rojiblancos after a few experienced and talented stars have left Diego Simeone's side since the window opened.
Over in the Premier League, Spurs appear to have themselves a world-class talent in Tanguy Ndombele, a player who initially seemed to be closer to a switch to Real. The former Lyon man has skill and a physical presence that should see him look at home in London, but that does not make it any less surprising.
Italian star Stephan El Shaarawy, 26, made a shock move to a Chinese Super League side in recent weeks – click through the gallery to see some more of this window's surprising transfers so far!
Which of these deals caught you unawares? Let us know in the comments section below.