Watch the horror tackle on Possebon here

Cristiano Ronaldo claimed his first goal of the season as Manchester United booked their place in the Carling Cup fourth round at Old Trafford last night, but what would otherwise have been remembered as a satisfying evening’s work was marred by a moment of madness from Emanuel Pogatetz.

There are occasions in football when the result seems almost incidental, and as Rodrigo Possebon was taken to hospital with a suspected broken leg, the victim — on his first-team debut — of an appalling challenge by the Middlesbrough defender, that appeared to be very much the case for Sir Alex Ferguson as the United manager reflected on the kind of tackle that can end careers.

If there was any justice, it was that Pogatetz’s red card swung the game in United’s favour, although Ferguson may not be pacified unless the FA takes firm action against the Austria defender, whose nickname of “Mad Pog” hints at an unsavoury side. A mandatory three-match ban should be the least that Pogatetz can expect.

“It’s not good, we hope it’s not the worst possible news,” Ferguson said. “For the kid to make his first-team debut and get an injury like that was pretty horrendous.

“For the ten minutes after, I think everyone was numb about it. It killed the momentum a bit, too. The thing about these challenges is that the opponent always claims his innocence. That’s what I can’t understand, he should have just walked off.”

The incident happened midway through the second half when, challenging for a ball that he would never have won legitimately, Pogatetz launched a shameful lunge at Possebon, the United midfield player feeling the full force of the defender’s studs. The four-inch gash high on the 19-year-old Brazilian’s shin said it all and he had to be given oxygen as United’s medical team attached a splint to his leg before carrying the player off on a stretcher and taking him to hospital.

As Pogatetz remonstrated against his dismissal, Ferguson tore into Colin Cooper, the Middlesbrough assistant manager, for attempting to absolve the player of blame. Gareth Southgate restored order, however, when he apologised to the United manager for what he conceded was a “poor tackle”.

“Their bench was out screaming that it was never a sending-off and there was nothing wrong with the player,” Ferguson said. “But at least Gareth Southgate was very good afterwards. He understood the gravity of it and was very apologetic, but it was a terrible tackle. I really don’t want to see it again.”

Southgate was unimpressed with Pogatetz, not least by the manner in which the sending-off handed United the initiative after Adam Johnson had put Middlesbrough back on level terms with a terrific volley to cancel out Ronaldo’s first-half header.

Ryan Giggs scored the decisive second, when he seized on a mistake by Chris Riggott to chip Brad Jones, and Nani added gloss to proceedings during the nine minutes of stoppage time played as a consequence of Possebon’s injury.

“Our first thoughts are with the lad, but in terms of the impact it [the sending-off] had on the game, we had just got ourselves back into it and then that knocked all our momentum,” Southgate, the Middlesbrough manager, said. “The last two years he [Pogatetz] has worked incredibly hard on his disciplinary record and that’s an unusual aberration for him.”

Ferguson had made 11 changes to the team who started against Chelsea at Stamford Bridge two days earlier, but with him perhaps being keen to guard against the risk of a repeat of the 2-0 defeat by Coventry City at this stage of the competition last season, Ronaldo, Giggs, Nani, Anderson and Nemanja Vidic were involved and it was a tactic that paid off.

Despite a brief Middlesbrough rally in the 56th minute, when Johnson hammered home a 20-yard volley after Vidic had only partially cleared Gary O’Neil’s cross, United were worthy winners. Unfortunately for them, their second victory of the season proved a bittersweet experience.

Manchester United (4-2-3-1): B Amos – R Da Silva, W Brown, N Vidic, J O’Shea – R Possebon (sub: D Gibson, 69min), Anderson – C Ronaldo (sub: C Tévez, 61), R Giggs (sub: Manucho, 85), Nani – D Wellbeck. Substitutes not used: R-R Zieler, T Cleverley, D Gray, R Eckersley.

Middlesbrough (4-1-4-1): B Jones – J Hoyte, D Wheater, E Pogatetz, A Taylor – M Shawky (sub: A Johnson, 46) – J Aliadière, D Digard, G O’Neil, S Downing – Afonso Alves. Substitutes not used: R Turnbull, C Riggott, M Emnes, J Arca, J Walker, T Craddock. Booked: Johnson. Sent off: Pogatetz. Referee: A Marriner.

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Sir Alex Ferguson, the Manchester United manager, has revealed what he told Cristiano Ronaldo during their meeting in July and conceded that the Portugal winger will leave the club at some point. Ronaldo made no secret of his desire to join Real Madrid this summer, but while Ferguson said that he could understand the Portugal forward’s reasons, he had managed to persuade him that he would be far better cementing legendary status in the manner of Eric Cantona than leave before that has happened.

“Just as Italians playing abroad all dream of playing one day for Juventus or the Milan clubs, so southern Europeans want at some point to play for Real Madrid or Barcelona,” Ferguson said. “So I understood what was going on in Cristiano’s mind when he declared that he wanted to join Real, but once we had talked, he accepted it was a move for the future. I pointed out how much better it would be to leave like Eric Cantona, with the fans loving and appreciating him.”