Chelsea have agreed a £7.5m deal to sign the Aston Villa goalkeeper Emiliano Martínez and are expecting Manchester City to make an offer for Enzo Fernández in the next 48 hours.Xabi Alonso identified the signing of a goalkeeper as a priority after Robert Sánchez struggled against Fulham last Monday and the deal for Martínez has gone through quickly. The Argentina international is out of favour at Villa after their acquisition of Zion Suzuki and is due to sign a two-year contract with the option of a further year.The signing of Martínez, who will be 34 next week, will raise questions over the future of Sánchez. Sources believe the Spaniard is unlikely to accept losing his spot as No 1 and may need to be moved on before the window shuts on Tuesday night.Quick GuideHow do I sign up for sport breaking news alerts?ShowIn the Guardian app, tap the Profile settings button at the top right, then select Notifications. Turn on sport notifications.If you already have the Guardian app, make sure you’re on the most recent version.If you don't have the Guardian app, download it from the iOS App Store on iPhone or the Google Play store on Android by searching for 'The Guardian'.It is unclear whether there is an obvious club for Sánchez to join and another complication for Chelsea will be working out what to do with Mike Penders, who was expected to challenge for the No1 shirt this season. There is a feeling that Penders could leave on loan. The highly rated 21-year-old Belgian spent last season on loan at Strasbourg.It is poised to be a busy end to the summer for Chelsea, who are also dealing with City’s attempts to sign Fernández. The Argentina midfielder is desperate to leave and was left out of the side for Thursday night’s Carabao Cup tie against Luton.Sources at Chelsea insist a deal is not close and that there has yet to be any communication from City. Chelsea are adamant that Fernández will be sold only on their terms. City missed an unofficial deadline to sign the midfielder for £120m this month and there have been suggestions the price could be higher because the end of the window is approaching.Chelsea also need to be able to strengthen their squad but they have little time to act. Chelsea are expected to make further checks on Alex Scott if Fernández is sold, although Bournemouth remain adamant the England Under-21 international will not be sold. Bournemouth knocked back a £64m bid for Scott last month and also rebuffed interest from Arsenal. Chelsea are also tracking Adam Wharton but Crystal Palace are determined not to sell the England midfielder.Chelsea may end up not looking for a direct replacement for Fernández but will not accept weakening their squad by helping out a rival.