The Eagles are thought to have been in talks with Blackburn Rovers defender Scott Dann and Blackpool winger Thomas Ince for the majority of the day, although those discussions now appear to be close to a conclusion.
"We're very close to signing three other players - we should have those done before the window closes. The medicals are all done and we're just finalising paperwork. We're very pleased with today, and I think the supporters will be when the final ones are announced. It's been a long, difficult day and we've got the four that we wanted, as long as we get them over the line," he told BBC Radio 5 live.