Chelsea goalkeeper Thibaut Courtois won the Copa del Rey during a loan spell at Atletico - as well as La Liga and the Europa LeagueBBC coverageHow to follow:Listen on BBC Radio 5 live and BBC local radio; text commentary on the BBC Sport website
Chelsea midfielder Danny Drinkwater is the only player missing for Wednesday's Champions League group match at Atletico Madrid.
England international Drinkwater has a calf injury and is out until October.
La Liga side Atletico have agreed a deal with Chelsea to re-sign the 28-year-old Spain striker Diego Costa.
However, the move will not be completed until January and is subject to the agreement of personal terms and a medical.
Who is Europe's hottest striker so far this season?Listen: Costa leaving Chelsea a relief for Conte - NevinCourtois back on familiar territory
Chelsea arrived in Madrid with five Spaniards in their squad - defenders Marcos Alonso and Cesar Azpilicueta, midfielders Cesc Fabregas and Pedro, and forward Alvaro Morata.
There is also a lot of attention on goalkeeper Thibaut Courtois.
The 25-year-old Belgium international spent three seasons on loan at Atletico before becoming Chelsea's number one.
In 2011-12, Courtois helped Diego Simeone's side beat Athletic Bilbao in the Europa League final before winning the Copa del Rey the following season after victory over city rivals Real Madrid at the Bernabeu.
Courtois also played in all but one game as Atletico won the league title in 2014.
How likely are Chelsea to progress?
Sports data specialists Gracenote Sports have simulated the remainder of the Champions League group phase one million times based on their current ratings for the clubs involved and their results to date and have come up with a probability percentage of each side progressing to the knockout stage.
Simon Gleave, head of analysis at Gracenote Sports, said: "Chelsea, like Manchester City and Manchester United, faced the weakest team in their group two weeks ago. So, although the scoreline was impressive, it has only slightly moved their chance of reaching the last 16, up to 74%.
"Chelsea's results against Atletico Madrid and Roma in the next two matches will make more of an impression on their chance of going through."
MATCH FACTSAtletico Madrid are unbeaten in their past four competitive games against Chelsea (W2 D2).Under Simeone, Atletico Madrid have won 18 of their 23 Champions League home matches.Chelsea are unbeaten in their past nine Champions League away games against Spanish opposition (W2 D7), drawing the past five.The Blues have reached the knockout stages of the Champions League 13 times in their previous 14 appearances.Chelsea have lost only one of their past 14 Champions League group games.This will be Simeone's 50th match as manager in the Champions League. His teams have conceded an average of 0.65 goals per game, the best ratio among managers with 20 or more games in the competition.
Source: bbc.com