Gary Neville says Manchester United will have to consider playing a back three if they want to keep picking Lisandro Martinez.
Argentina defender Martinez arrived at Old Trafford from Ajax in the summer for a fee that could eventually reach £55million, with Erik ten Hag having worked with the 24-year-old in the Dutch capital.
At 5ft 9ins the seven-times capped international is believed to be the shortest centre-back across the top divisions in Europe, and Neville says that lack of physicality means he may not be suited to playing a central defensive pairing in English football.
Martinez started alongside Harry Maguire in Saturday's trip to Brentford, but the pair looked all at sea as the Bees romped to a 4-0 victory to make Ten Hag's start to life as Manchester United boss the worst in 101 years, with John Chapman the last United manager to lose his first two matches in charge back in 1921.
Neville, who spent his long United career playing as a right-back and centre-back, feels that Ten Hag won't be able to keep picking Martinez unless he has more help at the back.
"Maybe on the left in a back three – that could potentially work," Neville told Sky Sports when assessing Martinez's display and discussing where he could play.
"Maybe playing in midfield, because we know he can do that. I think he’s got tenacity and, to be fair, I wouldn’t judge him at all at this moment in time.
"But to say he could play in a back four away at Brentford against [Ivan] Toney and [Bryan] Mbeumo – he physically can’t compete with them.
"I couldn’t when I was playing as a centre-back when I was younger, and I thought I was a decent centre-back who knew my position and knew the game. But I couldn’t do it because Gary Pallister had to keep coming over to swap with me.
"When I saw him [Martinez] swapping with Maguire in the first half at the long throws, it reminded me of Pally who used to swap with me.
"If you’re having to swap positions at centre-back to compensate for the other one it’s just not great and that’s what continually happened. They did target him in that first half."
Ten Hag - who cancelled a planned day off for the United players on Sunday - ultimately replaced Martinez with Raphael Varane at half-time, with the Argentinean one of three players he replaced at the break along with Luke Shaw and Fred.
However, he insisted that he could just as easily have taken any of his players off after a dreadful 45 minutes.
"They follow my instructions, but they make bad decisions," said Ten Hag of his players. "This is football, it is a game of mistakes and you get punished.
"I subbed three, but I could have changed them all. We want to bring some fresh energy into the game."
