Tottenham fans will not look back on January too fondly, as it was a defining month in their season.

In the space of four days, Spurs crashed out of both the League Cup and the FA Cup, meaning they only now have the Premier League and Champions League as a slim hope of achieving silverware this season.

What is worse is that they lost ground in their title chase as they lost to Man United at home at Wembley.

It was also a defining January for Tottenham after the summer transfer window where they infamously did not sign a single player. Fans and pundits alike were speculating whether the same would happen again or Tottenham would open their wallets.

With that in mind, these are the two biggest mistakes Tottenham made this transfer window:

Selling Mousa Dembélé

No Tottenham fan would argue that Mousa Dembélé was in the form of his life when he sustained an ankle injury in November. The Belgian midfielder had just come from a taxing summer with Belgium in the World Cup and looked slightly off the pace. Nonetheless, most Tottenham fans would have believed that he would eventually get back to his best.

But the 31-year-old was sold in January to Chinese Super League outfit Guangzhou R&F, which would have baffled many fans.

Of course, the 80-cap Belgium star only had half a season left on his contract and would have therefore left for free in the summer, but given the service that he has given to Tottenham and the fact that he could still play a part in their season, selling him for free at the end of the season may have actually been a better alternative to making money from him in January.

Subsequent injuries to Moussa Sissoko and Eric Dier had left Tottenham's midfield looking very sparse indeed, forcing them to rely on the relatively inexperienced Harry Winks and the 18-year-old Oliver Skipp. Dembélé's absence was certainly highlighted  during January and perhaps as the season goes on.

Not selling the fringe

Of course it is easy to say that Tottenham failing to sign a player over January was a mistake of theirs, just as it may have been in the summer. With injuries in the squad and fatigue, Tottenham certainly could have done with an extra face.

However, it has long been said that Tottenham need to unload of some of their unwanted players before they can sign anyone new, and that may have been an even greater mistake over the last month.

When thinking of unwanted Tottenham players, Vincent Janssen is probably top of the list. Mauricio Pochettino has made it clear that the Dutchman is not part of his plans and he is unlikely to play this season, particularly now Spurs are out of the FA Cup. Therefore, their inability to sell him not only wastes his career but fails to open up spaces and funds for Tottenham to sign any new players, which could prove to be their greatest error.