Ryan Giggs has urged Manchester United fans not to write off Victor Lindelof, pointing to Nemanja Vidic as an example of a player who has become a star after a slow beginning.
After Phil Jones was injured in the first half of Saturday's shock 2-1 away defeat against Huddersfield Town, Lindelof came off the substitutes' bench for what was only his second Premier League appearance.
The Sweden international made a costly mistake for the second goal scored by Laurent Depoitre, continuing a tough start to his United career that has also seen him struggle in the UEFA Super Cup defeat to Real Madrid and fail to force his way into Jose Mourinho's starting XI.
But United icon Giggs believes it is far too soon to jump to conclusions about Lindelof, who signed from Benfica for an initial €35 million in June.
"One player who has attracted a lot of criticism is Victor Lindelof but he certainly shouldn't be written off yet," Giggs, the club's former player and assistant manager, told Sky Sports.
"Some players come to the Premier League and bed in straight away and others can take six months or even a year, as it was for Patrice Evra, Jaap Stam and Nemanja Vidic, and they went on to be unbelievable players.
"You win together and lose together and you can't single out a player, especially when he hasn't been playing regularly.
"He's just got to knuckle down and come through this."
After the Huddersfield defeat, Ander Herrera criticised the "passion" of United's players, but Giggs feels that may not have been the best move.
"I am a little bit surprised at Ander Herrera's comments because you wouldn't really comment about your team-mates, you leave that to the manager," he said.
"When you start questioning your team-mates' work rates, even if they weren't at it, it can set a dangerous precedent.
"Losing to Huddersfield was obviously disappointing but you can never be surprised in the Premier League.
"You have to be right at it every weekend and Manchester United clearly weren't after two tough away games at Liverpool and Benfica."
Giggs has expressed an interest in the vacant Premier League managerial roles at Everton and Leicester City, having not held a role since leaving United when Louis van Gaal was sacked last year.