Chelsea sent scouts to Spain last week to keep an eye on Diego Costa, as well as Manchester United target Felipe Luis, according to talkSPORT.
Both Brazilian born players starred as Atletico thrashed AC Milan 4-1 to reach the quarter finals of the Champions League last week.
Chelsea have been heavily linked with free-scoring Costa, the man widely regarded as Jose Mourinho’s first choice to solve the Blues striker worries.
And now it appears they are ready to take on Manchester United for the signature of left back Felipe Luis.
Right back Cesar Azpilicueta has impressed on the left this season, although Mourinho is on the lookout for a long term replacement for Ashley Cole, who is set to see his contract at Stamford Bridge expire at the end of the season.
Both Premier League clubs have also been linked with Southampton left back Luke Shaw, although the 18-year-old is set to demand a fee in excess of £30million.
Luis is a slightly cheaper alternative, valued at around £20million, although the price could rise further with French money-bags Monaco also reportedly considering a summer move.