With Philippe Coutinho having become the second most expensive player in history and Alexis Sanchez completing his move to Manchester United, here are some of the biggest deals that could still happen before the window closes.
Click through the gallery above to see some big transfers that could still happen this month.
There currently seems to be a tug-of-war between Borussia Dortmund and Arsenal for Pierre-Emerick Aubameyang. The Gabon striker could potentially become one of the most expensive African players in history if the Gunners pay the £60 million (R1.02 billion) fee Dortmund are said to be holding out for, according to the Daily Mirror.
Aubameyang is understood to be keen to leave the Bundesliga side, while Olivier Giroud could move the other way in order to gain regular game time ahead of the 2018 FIFA World Cup.
Meanwhile, Pep Guardiola also seems keen to make at least one addition to his high-flying Manchester City squad. The Spaniard is reportedly close to activating Aymerica Laporte's €65 million (R961 million) release clause, as claimed by Marca.
The defender could end up not being Guardiola's only addition, with Shakhtar Donetsk midfielder Fred also linked with a January switch to the Etihad Stadium.
Tottenham Hotspur are reportedly also still keen to become active in this window, and have been heavily linked with Bordeaux winger Malcom, with reports from Brazil's UOL suggesting they are closing in on a £44 million (R746 million) deal.
Lucas Moura, who has been told by Paris Saint-Germain to find a new club in January, according to reports, is another name heavily linked with a Spurs switch, while Chelsea are said to be chasing AS Roma duo Edin Dzeko and Emerson Palmieri.
Click through the gallery above to see more big deals that could still happen this month, and let us know, in the comments section below, which of these transfers you would like to see transpire.