The Citizens have been tipped to delve into the transfer market to recruit a new goalkeeper amidst uncertainty over the long-term future of first-choice shot-stopper Ederson.
Speculation over Ederson's future has been rife for some time, with clubs in the Saudi Pro League having been credited with an interest in the Brazil international since the summer.
An exit from the Etihad Stadium, where Ederson has spent the last seven years of his career, did not materialise in the summer and Pep Guardiola has since talked up the 31-year-old's importance for the Citizens.
Ederson continues to be linked with a future departure, though, and, Man City are believed to be eyeing up potential replacements as they are aware that their No.31 now has less than two years remaining on his contract.
Man City put off by Costa valuation?
According to CaughtOffside, Man City will consider a move for Porto's Costa if Ederson decides to seek pastures new.
The report states that Guardiola 'highly appreciates' Costa's talents and would be interested in luring the Portugal international to the Etihad if Ederson departs.
Costa himself is said to have expressed an interest in moving to the Premier League if the opportunity presents itself, with the 25-year-old believed to be keen to challenge himself at a higher level.
However, Costa has a release clause in his Porto contract worth €75m (£62.7m) and Man City believe that this valuation is too high.
The Citizens are said to value the goalkeeper around £25m below Porto's asking price - between €45m (£37.6m) and €50m (£41.8m).
Costa, who has also been linked with Barcelona, has spent his entire club career with Porto, joining their academy back in 2011 before making his professional debut in September 2019.
The Switzerland-born shot-stopper has since kept 69 clean sheets in 165 senior appearances for Porto across all competitions, including five shutouts in eight Primeira Liga matches at the start of this season.
Costa has won a total of eight trophies with Porto over the last five seasons, including two Primeira Liga titles and four Portuguese cups, while he has also been named Primeira Liga Goalkeeper of the Season on two occasions and won the Golden Glove last season after keeping 14 clean sheets in 33 league games.
Who else could replace Ederson if Man City opt against signing Costa?
Should Man City decide against a move for Costa, one name who they could target is highly-rated Lille goalkeeper Lucas Chevalier, with one report claiming that the Citizens have added the 22-year-old to their shortlist.
Guardiola could also consider promoting number two goalkeeper Stefan Ortega, who is keen to play regularly at Man City and signed a contract extension in the summer until June 2026.