Chelseahave completed the signing of Augsburg left-backAbdul Baba Rahman, who joins the club for an undisclosed transfer, the team announced Sunday.Mirror confirmed the 21-year-old's move to Stamford Bridge.The Ghanaian left-back exits the Bundesliga one year after joining Augsburg, which he helped to an excellent fifth-place finish last season. He previously representedAsante Kotoko in the Ghanaian Premier League and Bundesliga 2 sideGreuther Furth.Rahman finished last season with four assists in 31 domestic appearances for the German club, averaging a team-high rating of 7.37/10 on WhoScored.com. He possesses lightening pace, quality dribbling skills and the aggression that could make him a future star at Chelsea.WhoScored.com noted one of Rahman's most impressive stats:Augsburg sporting director Stefan Reuter previously told Augsburger Nachrichten(h/t Peter O'Rourke of ESPN FC) that Rahman would only be sold for an "extreme" sum," a reflection of his ranking among the side's most important players.Atletico Madrid have agreed to a 16 million deal with Chelsea for the return of Filipe Luis, according to AS (h/t Football Espana). The Brazilian made just 15 Premier League appearances under Jose Mourinho last season and was unable to oust Cesar Azpilicueta from the team.Rahman will now take on the seemingly difficult task of dislodging one of the Blues' most reliable players. Azpilicuetaisn't a great offensive star, but his positioning and ability to win the ball back have added steel to Chelsea's defence over the last two seasons. Rahman can be considered the more explosive alternative.This is his fourth club since 2011, so Rahman will now be looking to make it at one of Europe's top sides. He has the quality and ambition to continue improving, but at such a young age, he can be expected to take a rotational role with his new team. Click here to read full news..