Chelsea have agreed a deal in principle to sign the Brighton goalkeeper Robert Sánchez for a fee worth up to £25m. Sánchez, who is due to undergo a medical, lost his place under Roberto De Zerbi last season. Signing a goalkeeper has been a priority for Chelsea and they want the Spain international to provide competition for Kepa Arrizabalaga. Chelsea have moved quickly in negotiations over Sánchez, who is set to cost £20m plus £5m in add-ons, and they remain in talks with Brighton over a deal for the Ecuador midfielder Moisés Caicedo. Brighton want £100m for Caicedo and have rejected several bids for the 21-year-old. Mauricio Pochettino is desperate for additions in midfield, where he is short on depth and experience before his new side host Liverpool on the opening weekend of the season. Conor Gallagher and Enzo Fernández are the only senior midfielders after the departures of Jorginho, Ruben Loftus-Cheek, Mateo Kovacic, N’Golo Kanté and Mason Mount. Chelsea have made one midfield signing, buying Lesley Ugochukwu from Rennes for £23.5m, but the 19-year-old is expected to go on loan to Strasbourg. Competition for Gallagher and Fernández comes from talented but raw youngsters – Cesare Casadei, Andrey Santos and Carney Chukwuemeka. Pochettino said he wanted more experience after Chelsea ended their pre-season tour of the US by drawing with Borussia Dortmund. The club are reluctant to meet Brighton’s asking price for Caicedo and have considered alternative targets, including Leeds’s Tyler Adams and Ajax’s Edson Álvarez. Well-placed sources, though, have suggested Chelsea’s desperation to sign Caicedo will lead them to pay close to £100m. The aim for Pochettino is to strengthen in a few key areas. Chelsea had considered spending big on a No 1 goalkeeper – they had targeted André Onana, who ended up joining Manchester United from Internazionale, and Milan’s Mike Maignan – but revised their plans after failing to find a buyer for Arrizabalaga. They sold Édouard Mendy to Al-Ahli. The decision was made to find a cheaper goalkeeper and Sánchez will not blow a big hole in their budget. Ben Roberts, who heads Chelsea’s goalkeeping department, worked with Sánchez at Brighton and is a big fan of the 25-year-old. Sánchez is adept with his feet but lost his place to Jason Steele and Brighton have signed Bart Verbruggen from Anderlecht this summer. Chelsea are set to loan their young American goalkeeper Gabriel Slonina to KAS Eupen in Belgium. Much of the focus for Chelsea has been on decreasing the size of their squad. Pochettino wants further sales and Chelsea are trying to shift Romelu Lukaku, Hakim Ziyech and Callum Hudson-Odoi, who is wanted by Fulham. Juventus are trying to sign Lukaku and have looked to push through a deal for the striker by offering Dusan Vlahovic to Chelsea. Pochettino is interested in a forward but it remains to be seen whether he is interested in Vlahovic. Chelsea have been pleasantly surprised by the impact Nicolas Jackson has made in attack during pre-season. Jackson has linked well with another new arrival, Christopher Nkunku. However there was a scare for Chelsea when Nkunku limped off with a knee injury against Dortmund. Although there is optimism the France forward has not sustained any serious damage to his left knee, it is unclear whether he will be fit to face Liverpool on 13 August.