Real Madrid have announced an agreement to sign highly-rated teenage defender Jesus Vallejo from Real Zaragoza.
Aston Villa have continued their spending spree after securing the services of Rudy Gestede from Blackburn on a five-year contract.
Celtic will step up attempts to renew the contract of Georgios Samaras after tying down fellow striker Anthony Stokes for two more years.
Stokes signed a new three-year contract on Tuesday that commits him to Celtic until the summer of 2016.
And chief executive Peter Lawwell is looking to secure new deals for Greece forward Samaras and Wales midfielder Joe Ledley, whose contracts both expire at the end of the season.
Lawwell said: "We are meeting Samaras's agent next week. Ledley we are in constant discussions, we are to-ing and fro-ing on that."
Swedish defender Mikael Lustig is also in the frame for a new contract while Lawwell is relaxed about Kris Commons' situation.
"We haven't done anything on Kris," Lawwell said. "He has a year and a half to go and I think he is quite happy with that.
"Mikael has a year and a half to go and we are hoping to start conversations with his people as well. He has been fantastic, a great buy, a great find, and he has done really well for us."
Celtic this summer sold Kelvin Wilson, Gary Hooper and Victor Wanyama, acquiring about £20million in the process, but Lawwell is hopeful he will secure further commitment from the bulk of Neil Lennon's team in the long run.
"Celtic has got a great pull," he said. "These guys seem to be happy here. They have Champions League football.
"I think they are aware that when players leave Celtic, they leave something behind. They certainly miss it.
"Even going to the English Premier League, for a lot of people it doesn't make up for what they have here at Celtic."