Doncaster have made forward Dany N'Guessan their sixth summer signing.
Tottenham have confirmed that Romanian defender Vlad Chiriches has completed a move to Napoli.
Sigurdsson arrived from Tottenham's pre-season tour of the USA on Wednesday morning and it is believed the Iceland international will sign a deal worth £8million to return to the Liberty Stadium, where he previously spent a season on loan.
The conclusion of this deal will allow Swansea keeper Michel Vorm to complete his move to Tottenham, having agreed terms over £2m deal and successfully completed a medical in Netherlands on Tuesday.
Vorm was convinced to join Spurs' goalkeeping department and compete with France No 1 Hugo Lloris, confirming his imminent move to Dutch newspaper De Telegraaf.
He said: "Every club has two top goalkeepers in their squad. It suits the club's philosophy that there are two of us with Hugo and me, especially when we see that Tottenham is active in a lot of competitions."
Sky Sports understands Wales left-back Ben Davies has already completed his transfer from Swansea to Spurs having been pictured in his first training session in Toronto, although the move has still to be formally announced.
Both Tottenham and Swansea are currently on pre-season tours of the USA and this has allowed them to conduct lengthy, complicated negotiations involving all three players.