Chelsea will host Manchester City in the fifth round of the FA Cup on Sunday. .
Fernando insists Manchester City must not obsess over provocative Chelsea striker Diego Costa as the teams prepare to meet in the FA Cup.
City will the make trip to Stamford Bridge for Sunday's fifth-round clash against Chelsea, with all eyes set to be on Costa.
The feisty Spain international has enjoyed some heated exchanges with City, and the match in London is expected to be no different.
Fernando is braced for what the 27-year-old has to offer.