The transfer window is always an exciting period for football fans and over the years Chelsea have made numerous signings, many of which were triumphs.
However, for every batch of arrivals, there are some that are successful and some that fail to live up to expectation.
Whether it is the extortionate fee, the unlucky vein of form or lack of game time, here are the five most disappointing signings made by Chelsea.
5. Tiemoue Bakayoko
Tiemoue Bakayoko has struggled to find any vein of form since joining the Blues for £40 million in 2017 from AS Monaco.
High expectations came with the midfielder having enjoyed a successful Champions League campaign with Monaco, but he did not live up to the hype.
The 24-year-old went on loan to AC Milan and showcased glimpses of promise however is yet to justify his fee on English soil.
He made 43 appearances for the Blues in all competitions having started 34 and contributing to just six goals. The Frenchman lost 36 of his 76 aerial battles in the Premier League as well as losing 155 out of 319 duels.
4. Sebastian Veron
Sebastian Veron signed for Chelsea from Manchester United in 2003 for £15-20million and sold the Argentine for just under £2million to Estudiantes in 2006.
The seasoned midfielder only played 14 times for Chelsea providing one goal and one assist. Upon confirmation of his transfer to the Blues Veron became accusatively the most expensive player in the world.
3. Mark Bosnich
Mark Bosnich was signed from the Red Devils in 2001 on a free transfer. The Australian goalkeeper was on a reported £45,000 a week and played seven times for Chelsea conceding seven over two seasons.
Bosnich was soon banned from football for nine months having failed a drug test in 2002 and subsequently sacked by the Blues.
2. Winston Bogarde
Another centre-half. Winston Bogarde will go down as one of Chelsea's worst transfers.
The Dutchman was signed on a free transfer from Barcelona in 2001 on a four-year contract earning a reported £40,000 a week.
Bogarde failed to make an impression at the Blues making just 12 appearances, 11 of which came in the first season.
He was often encouraged to move on however a loan nor transfer was agreed and decided to see out his contract earning nearly £10million in four years.
1. Papy Dijlobodji
Papy Dijlobodji signed for Chelsea for a reported £3million from Nantes on transfer deadline day ahead of the 2015/16 season.
The Senegalese defender made only one appearance for the Blues before being sent out on loan to Werder Bremen the following January.
Upon return to Stamford Bridge the 30-year was soon sold to Sunderland.
In his one game, the defender was the ultimate one minute wonder.
Djilobodji was substituted on with one minute remaining in a 4-1 over Walsall in the EFL Cup Third Round. Chelsea and the 'one-minute super-sub' managed to retain their lead in the remaining.