The 31-year-old winger joined Derby last summer on a free transfer and featured 44 times for Warne’s side last term.
This season, Mendez-Laing is in impressive form and has scored four times in the last five league games for Derby.
Barker pointed out that Mendez-Laing is a player who uses his athleticism and physicality to dominate defenders and he warned the Derby boss that the forward is a different player when he is tired.
The ex-Rams star stressed the importance of keeping Mendez-Laing fit this season and added that the winger is unstoppable when he is in form.
“He is a player we need to keep fit”, Barker said on Rams TV.
“He is a player we have to be careful with at times over the course of the season because he is a player that uses his athleticism and his physicality to dominate defenders and as soon as it starts tipping the balance and he looks tired and he looks fatigued, he looks like a different player.
“I think Paul rested him maybe six or seven weeks ago and actually coming back from that, the game where he was dropped and rested and he came back the following week is where he picked up his form.
“So there might be a few moments where the manager has to be careful, but when he is playing and when he is on song, he can be unstoppable.”
Derby will travel to Vale Park on Tuesday and Mendez-Laing will be hoping that he can continue his impressive form against Port Vale.
