Jamie Carragher has praised Lisandro Martinez for being a “warrior” on the pitch and apologised for doubting the Man Utd defender when he first came to the Premier League.

The Argentina international made the move from Eredivisie giants Ajax to the Red Devils in the summer transfer window in a deal worth £47m initially plus another £8.5m in potential add-ons.

There were doubts from Carragher and other pundits that the Man Utd defender could succeed in the Premier League due to his 5ft 9in frame – but the centre-back has proved everyone wrong.

Not only has he been one of Man United’s best signings this season, alongside Casemiro, but he also helped Argentina to win the World Cup in the winter.

Speaking back in August, Carragher said: “That’s small for any player on the pitch in some ways now, really.

“You think how big and powerful players are. When you think of how that could affect Man Utd set piece wise, if one of your centre-backs is really small, you’re relying so much on the other centre-back to deal with things aerially coming into the box, so I think that could be a problem.”

But Carragher admits he got it wrong about Martinez and that the Man Utd centre-back has “made a huge difference” to Erik ten Hag’s side this summer.

Former Liverpool defender Carragher told Sky Sports: “[‘Too short to play in the Premier League’] that’s not about Lisandro Martinez, that’s about any centre-back coming to the Premier League whose well under six-foot you think is going to have a problem.

“But he hasn’t and every player has weaknesses whatever that may be, whether it’s physically or technically, and the best players hide the weaknesses, nobody’s a perfect player. I just looked at him and though how can you overcome that in the Premier League.

“I wasn’t the tallest centre-back and I used to go into games worried that I’m going to get found out and bullied. At times you lose big challenges and goals. I thought he’s two or three inches shorter than me.

“But just like with Casemiro, it’s a massive drop off when Martinez is not in the Manchester United team defensively but also his ability on the ball and playing out from the back.

“He’s a warrior, he’s a leader and when you think of that spine of the team certainly him and Casemiro, two new signings, they’ve made a huge difference.

“So apologies Lisandro and all Man United fans can you stop tweeting me about Lisandro Martinez now please!”