Boro manager Steve McClaren told the club’s official website, www.mfc.co.uk: “It’s a big blow to lose Ugo in this way. He’s a huge influence on the team and a big part of our defence.

“But we had a similar setback with Juninho’s knee injury last year and we bounced back from that. As we did then, we just have to get on with it.

“Naturally, we wish Ugo all the best. What we want is to see him making a full recovery and that will take time.

“His absence creates an opportunity for others. Things like this can happen and that’s exactly why we bought Chris Riggott from Derby in January. It’s an opportunity for both Chris and young Andrew Davies to stake their claims.”

Ehiogu suffered in the injury in Boro’s final home game of last season, against Tottenham, but the extent of the problem has only know been revealed by scans.

McClaren added: “He had scans soon after the Spurs match. Unfortunately, they didn’t reveal the full extent of the injury, as can often be the case.

“It was believed he had suffered bone bruising so he has been resting the knee over the summer.

“But when he joined the other lads for his fitness assessment on Thursday, the knee became swollen. We sent him for further scans which this time revealed the rupture.”

The news is a major blow to McClaren’s preparations for the new season, which will now have to begin without Ehiogu, who was the club’s record signing when he moved from Aston Villa three years ago.

Ehiogu, who has four England caps to his name, has been a Boro regular alongside fellow former Villa defender Gareth Southgate but may now not return to Premiership action until Christmas.