Sir Alex Ferguson's defensive concerns are mounting after Rio Ferdinand left the Riverside with his foot in a protective case following Manchester United's 2-2 draw with Middlesbrough. With a crucial phase in United's challenge for the Premier League and Champions League beckoning, Ferdinand looks likely to join fellow centre-back Nemanja Vidic, who is already out injured for three weeks, on the sidelines for this week's Champions League second leg against Roma.

"Hopefully it's not serious with Rio but he was limping for too long," said Ferguson. "The danger was to keep carrying on with him when he was limping and not playing at his full performance level. But Pique came on and did absolutely terrific, he was absolutely marvellous and I think that helped us."

Ferguson conceded that the result might easily have gone the other way, but maintained that United's title challenge remains firmly on track. "We could have lost the game there's no question, they had some chances and at times our defending was a bit haphazard I thought. But at other moments we could have won the game because some of the quality of our football was terrific. Middlesbrough also produced some great moments and it was just a fantastic game.

"The nature of the club is that we never give in and that's a great quality to have at this time of year. It sends out a signal to everyone, and our players and fans in particular, that we will never give in. We will be stretching ourselves in every game as long as we can. That point could be important, absolutely. Our goal difference is good obviously, but we cannot take anything for granted. I said some weeks ago consistency will win us it and I think the most consistent team will do that and I hope that it's us."

Middlesbrough manager Gareth Southgate, meanwhile, felt that his side had United "rattled." Southgate's side, who were only narrowly beaten 1-0 by Chelsea last weekend, came from behind to lead United 2-1 thanks to Afonso Alves's first two goals for the club, before Wayne Rooney struck with 16 minutes of the game left to add to Cristiano Ronaldo's early strike. "I am happy with the way we played," said Southgate. "We had a full house today and we gave a good account of ourselves so I am pleased.

Boro had United on their heels for much of the game and but for a series of excellent saves by Edwin Van der Sar might have had the game won before Rooney's deflected equaliser. And although United laid siege to Middlesbrough's goal in the final 14 minutes, Southgate felt his side more than matched the defending champions. "We were up against a team that are both outstanding to watch and to test ourselves against and we had them rattled," he added. "Both the goals we scored were good goals and we had them rattled.

"The team performance was excellent. We answered most of the questions and had them on the back foot for the majority of the game. I've spoken to the players afterwards following recent games. We've now been to Chelsea, Arsenal, Aston Villa and given a good account of ourselves. They are a young group of lads who will grow as a team."

Southgate also praised Alves after crowning a memorable performance with a deserved two goals. "I felt in training he was looking sharp and you get a feel for these things," he said. "He has shown the quality he has got. There is still more to come from him. He looked sharp, has a good temperament and his goals were crucial but I think we still won't see the best of him until the summer."

The draw takes Boro a point above Wigan, in 14th place, while United's lead at the top is now just three points ahead of Chelsea. United's disappointing afternoon was compounded by an injury to Rio Ferdinand, who went off injured midway through the second half.