England goalkeeper Fraser Forster does not know if he will still be at Celtic when they next play in Europe.
Norwich captain Sebastien Bassong has signed a new two-and-a-half-year contract.
Dundee United have signed former Portsmouth forward Nadir Ciftci after agreeing exit deals with both Brian McLean and Richie Ryan.
Former Turkey Under-19 international Ciftci, who can play through the centre or out wide, has penned a two-year contract after impressing manager Jackie McNamara on a three-week trial spell.
The 21-year-old, who made 19 appearances for Portsmouth, was available on a free transfer after leaving NAC Breda in his native Holland.
In a club statement, McNamara said: "Nadir has really impressed me. He will become an important member of our squad.
"He is strong, clever, has pace and an eye for goal. He has quickly become part of the squad and is a great guy to have around the dressing room.
"His desire to sign for Dundee United was obvious because he had more lucrative options but made it clear he wanted to progress his career at Tannadice."
Ciftci, United's ninth summer signing, added: "This is a fantastic club with great players and coaches. I want to join Dundee United because I know I can become a better player here.
"The players are not only good footballers but also have made me feel so much part of the club since I arrived. The fans have also made me feel welcome. I am delighted to have signed."
United earlier announced that both McLean and Ryan had left by "mutual consent" and "with the best wishes of all at the club".
McNamara told Ryan earlier this month that he would be a peripheral figure if he stayed while McLean returned home early from the club's pre-season tour to hold talks with Ross County.
Former Rangers, Motherwell and Falkirk defender McLean, 28, made 34 appearances for the Tayside club after joining from Preston on a two-year contract last summer.
McNamara, McLean's former Falkirk team-mate, took former Chesterfield central defender Neal Trotman on trial earlier this week.
McNamara had earlier signed centre-back Calum Butcher, while Paul Paton, a summer arrival from Partick Thistle, can play the right-back position that McLean sometimes filled.
Midfielder Ryan made 18 starts and 26 substitute appearances after joining from Sligo Rovers 18 months ago.
United dropped their interest in Graham Carey and Jean Yves Koue earlier this week.