Former Manchester United midfielder Owen Hargreaves fears for Victor Lindelof.
Lindelof was at fault in defeat at Huddersfield.
Hargreaves told BT Sport: "He's really really struggled. Obviously at Benfica he played incredibly well in the Champions League, some great performances.
"But we saw him against Real Madrid in the UEFA Super Cup he really struggled and today, both goals he was involved in.
"He was thrust into action when Phil Jones went off injured and he's come on and really really struggled.
"For Mourinho you have to earn his trust and I think today he's lost some of that with his performance."
Source: tribalfootball.com