Celtic full-back Mark Wilson accepts Tony Mowbray was right to warn his players over their futures following the 1-0 Europa League defeat by Hamburg.
Mowbray admitted he had to improve the quality of his squad after he suffered his third European home defeat. Scott Brown, Shaun Maloney and Scott McDonald had the best first-half chances but Celtic were sloppy in possession and they looked a beaten team after Marcus Berg fired home from 20 yards in the 63rd minute.
"It is down to the players to prove that they are good enough to stay at this club and play for these supporters, come January," the Parkhead boss said.
"We will try to find the right players of the right quality to lift the team and we are working hard behind the scenes to find those players."
Wilson - who has started each of the last four games, which Celtic have failed to win - admitted his own future had crossed his mind.
"He's a new manager and since he has come in, the players haven't set the place alight," Wilson said.
"It's been a pretty disappointing start to the season, to be honest.
"So I think he has got a point, he can only judge the players on what he has seen and it's been poor.
"With a new manager you're always playing for your career but when you start the season quite poorly, especially in the last four weeks, it creeps into your mind."
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