Kevin Phillips has compared Bailey Wright's importance to Sunderland to that of Tyrone Mings to Aston Villa, or Son Heung-Min's to Tottenham Hotspur.
The Bristol City defender moved on loan to the Black Cats last month, but will miss the majority of the rest of the season after limping off in their 1-0 victory at Oxford United on Saturday.
Yesterday Sunderland boss Phil Parkinson confirmed Wright will be out for two to three months.
With the Australian out of contract at the Robins in the summer and likely to leave Ashton Gate, it is a blow as he looks to try and settle in at the Stadium of Light.
Wright has made five appearances for Sunderland since moving in January, with the Black Cats keeping a clean sheet in each, and Phillips says he has had a big impact on Parkinson's side.
He told Football Insider:"A big blow. I thought he was awesome on Saturday.
"Afterwards, Phil was concerned but Ozturk can step in.
"The biggest thing for me, behind the turnaround, is that Phil has stuck with the same team now for this period when they have been successful. Very rarely has he changed it.
"There is always going to be times where you are forced to make a change but when you lose an influential player like Bailey or Mings at Aston Villa or Son at Spurs – it can affect you.
"It is going to be interesting to see how Sunderland will play without him in the squad."
City boss Lee Johnson sent his support to Wright after the news, backing the defender to bounce back.
He said: "There's not much you can say apart from 'I'm here for you mate'.
"It's football, it's the truth of football that players get injured and he'll be gutted and disappointed but as I say, it's a footballing fact and he's a strong character so I've got no doubt that he'll be fine."
