West Bromwich Albion manager Slaven Bilic says he is "really disappointed" Ahmed Hegazi was allowed to leave the club and that he was assured the defender would stay.
Hegazi, 29, has moved to Saudi Arabian club Al-Ittihad on loan but will sign permanently at the end of the season.
Bilic said the Egypt central defender had been part of his plans for Monday's 1-1 draw at Brighton.
"He has experience. He is a top professional," Bilic told BBC Sport.
Hegazi made his first start of the season for West Brom in the 0-0 home draw with Burnley on 19 October.
Bilic, 52, added: "I wanted him to stay and he wanted to stay and then something happened and then he is off although I had assurances from the club that he would stay.
"That happened yesterday. Of course I am not pleased. I am really disappointed because we need players. There is of course the economic side but we are a football club."
Hegazi made 104 appearances for West Brom and started 14 games last season as they won promotion to the Premier League from the Championship.
'A big insult' - analysis
Former Everton midfielder Leon Osman on BBC Radio 5 live:
It seems a strange decision. A guy in your team and in your plans and is suddenly sold the next week. You can understand why he is disappointed.
The transfer window is closed and that is the squad you have got. To sell a player who has just played in the first team is a big insult to the manager as much as anything else.