Nicolas Raskin is set to miss up to six weeks through injury.
The Rangers midfielder was forced off against Ajax in a pre-season friendly last weekend sparking fears of a lengthy layoff.
Raskin was spotted leaving the stadium in the Netherlands on crutches and using a protective boot after being on the receiving end of a heavy challenge from Branco van den Boomen.
Now, Philippe Clement has provided an update on the 23-year-old as he admitted he expected the injury to be worse.
"Raskin will be out for five to six weeks.
"I expected it to be worse if I saw him straight after the game but still it is a really bad injury, bad timing also because we are going to miss him in the beginning of the season that is clear."
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Clement also revealed Todd Cantwell and James Tavenier are nearing returns for Rangers having not played in any pre-season outings so far this summer.
"James Tavernier is getting better, he is close to training with the team," he said. "And Todd [Cantwell] is training with the team but is not ready to play with the first team so he will play with the second team on Saturday."
The update comes as speculation continues over a transfer exit from Rangers for Tavernier this summer with Turkish club Trabzonspor interested.
It's claimed an initial bid was rejected but reports claim the Super Lig club could return to the table to try and sign the Ibrox captain.
