Graphic: United shot down

For the second time in a little more than 48 hours, a dramatic late goal transformed the mood inside Old Trafford, but this time Manchester United were on the wrong end of it and could have no complaints. Even when it briefly seemed last night that they had papered over the yawning cracks that could be seen during another slipshod display, they looked like a flagging team whose luck was in serious danger of running out.

That was one conclusion as the dust settled on this absorbing encounter, with Porto’s supporters celebrating the 89th-minute goal from Mariano that arguably makes them marginal favourites in the second leg at the Estádio do Dragão a week today.

No English team have beaten Porto away from home in 11 visits and, while that is exactly the kind of challenge that usually brings out the best in Sir Alex Ferguson and his players, the more immediate task for the United manager is to reinvigorate a squad that suddenly looks low on energy and, more surprisingly, self-belief.

Fatigue was inevitable last night, two days after a draining 3-2 victory over Aston Villa. Ferguson played down the idea of a more lasting problem, no doubt encouraged that his team again continued to battle until the very end of another match that was played at a high tempo throughout, but something is not right about United at the moment.

The most glaring problems are in a once impregnable defence that have conceded ten goals in the past four matches, but a collective malaise has swept the team since Liverpool’s 4-1 win at Old Trafford 3½ weeks ago and, while Federico Macheda’s stoppage- time winner against Villa was seen as an adrenalin shot at the time, its effect proved short-lived.

Porto should take much of the credit for that. They have usually suffered on their visits to England, losing 4-0 away to Arsenal in September and 4-1 away to Liverpool last season, but, like Villa, they took the game to United from the start and were unfortunate not to have more than a fourth-minute goal from Cristián Rodríguez to show for a highly accomplished first-half performance.

While a dreadful mistake from Bruno Alves allowed Wayne Rooney to equalise, justice was at least partially done in the 89th minute when Mariano punished yet more careless defending from United, four minutes after Carlos Tévez, a substitute, seemed to have given Ferguson’s team a flattering 2-1 win.

Ferguson and his staff must find a way to coax players such as Nemanja Vidic, Patrice Evra and Michael Carrick back to their best form and hope that the return from injury of Rio Ferdinand and Dimitar Berbatov can bring back much-needed poise.

United were nervous and totally unconvincing in the first half last night and by the time the half-hour point had been reached, Uefa’s statistics declared that Porto had mustered eight goal attempts to the home team’s two. Nor were those figures misrepresentative as Porto had run rings around a chaotic home defence, but the small mercy for United was that that one of their attempts had yielded a goal, Rooney showing great anticipation, then composure, to punish a calamitous back-pass from Alves in the fifteenth minute.

Terrible defending, though, was almost the exclusive preserve of United, their back four almost unrecognisable from that which went 14 Premier League matches without conceding a goal over the winter months. The personnel alone cannot explain that — John O’Shea and Jonny Evans filled in well on numerous occasions during the record-breaking sequence, so it is hard to argue that they, though poor last night, were a reason for the insecurity, rather than two of its most glaring symptoms.

Little wonder that Porto’s confidence grew as opportunities presented themselves in that first half. Lisandro gave Evans the slip in the third minute and hit a fierce rising shot that Edwin van der Sar could not hold. From the resulting corner, United cleared, but Cristiano Ronaldo, for neither the first nor the last time, carelessly lost possession, allowing the excellent Lucho González to tee up Rodríguez, who stepped inside Evans and curled a left-foot shot past Van der Sar for a goal that silenced Old Trafford.

After Rodríguez, Lisandro and Raul Meireles threatened in quick succession, Ferguson abandoned a disjointed 4-3-3 formation in favour of 4-4-2, which stabilised things somewhat. Ronaldo tested Helton, the goalkeeper, with a fine downward header from O’Shea’s cross, while Rooney almost caught out Helton early in the second half with a disguised shot that was dipping under the crossbar.

Rooney had a hand in Tévez’s goal in the 85th minute, flicking on Gary Neville’s throw-in intelligently to allow the Argentina forward to give United what looked like a slight advantage going into the second leg. But to Ferguson’s horror, his defenders were sucked towards the ball as Cristián Sapunaru crossed from the right, with Mariano left unmarked to beat Van der Sar. Not for the first time in recent weeks United had been rocked back on their heels. The question is whether they have it in them, physically and mentally, to respond.

Manchester United (4-3-3): E van der Sar — J O’Shea (sub: G Neville, 72min), N Vidic, J Evans, P Evra — M Carrick, P Scholes (sub: C Tévez, 72), D Fletcher — Park Ji Sung (sub: R Giggs, 59), W Rooney, C Ronaldo. Substitutes not used: B Foster, R Eckersley, Nani, F Macheda.

Porto (4-3-3): Helton — C Sapunaru, Rolando, B Alves, A Cissokho — Lucho Gonzalez, Fernando, Raul Meireles (sub: Tomas Costa, 79; sub: Andrés Madrid, 90) — Lisandro, Hulk, C Rodríguez (sub: Mariano, 80). Substitutes not used: Nuno, M Stepanov, E Farias, T Sektioui. Booked: Alves, Helton.

Referee: K Plautz (Austria).