Sir Alex Ferguson must wish that Portsmouth had never been promoted to the Premier League. His Manches-ter United team have won only once at Fratton Park in their five visits in the competition and last night their unconvincing start to the season stumbled on as they squandered an early lead and finished the match with ten men after Cristiano Ronaldo was dismissed six minutes from time, apparently for head-butting Richard Hughes, the Portsmouth defender.

Paul Scholes had put United ahead after 15 minutes from a pass by Carlos Tévez, who was making his debut, but they failed to press home their advantage and Benjani Mwaruwari headed an equaliser in the second half. Sulley Muntari, of Portsmouth, was shown a second yellow card after 83 minutes for a foul on Michael Carrick, but there was even more drama to come with Ronaldo’s dismissal.

“Cristiano was responsible for falling into the trap [of provocation], which has happened to him a few times,” Ferguson said. “It left us with only ten men and he’ll be missing three games now. It’s a big blow.

“We played some fantastic football at times and had to contend with some of their physical stuff. We were wasteful with some of our chances and we were unlucky not to get three points.”

Despite the absence of the injured Sol Campbell from their defence, Portsmouth remain unbeaten at Fratton Park since losing 2-0 to Chelsea on March 3 and this result will put them in good spirits for a difficult sequence of fixtures against Chelsea, Arsenal and Liverpool that they face after Saturday’s home match against Bolton Wanderers. However, United left Hampshire believing that they should have won after spending most of the first half and a good deal of the second on the attack.

With Lauren also missing after turning an ankle in training, the Portsmouth back four had a makeshift look about it and, after 15 minutes, Tévez was allowed to collect the ball under very little pressure and work it to a central position on the edge of the penalty area, where Scholes lashed it powerfully past the right hand of the diving David James with a rising shot.

It was Scholes’s 96th Premier League goal and makes him United’s leading scorer in the competition, with one more than Ruud van Nistelrooy.

With Nani providing trickery on the left and Ronaldo making inroads at will down the right, it looked as though the home defence would be overrun. A second goal seemed certain when Tévez collected the rebound after James had saved Ronaldo’s shot at full stretch, but Portsmouth managed to scramble the ball away before the Argentina forward could convert the chance.

Portsmouth’s attack, in which David Nugent was operating as a lone forward, was making little impression despite the typically persistent urgings of the home crowd. An optimistic and extremely ill-directed shot from distance by Sean Davis, in his 50th league appearance for Portsmouth, proved to be their only effort at goal during the first half.

Harry Redknapp’s system, with Mwaruwari operating in an unfamiliar role on the right of midfield, had failed to contain United and, at the same time, was frustrating his own team’s attacking instincts.

The manager had to make changes at the interval, but they might have backfired when Nani skipped past Noé Pamarot before he had adjusted to his new role at right back. Fortunately for the defender, James stuck out a leg to deny the former FC Porto winger and Portsmouth had a narrow escape moments later when Tévez volleyed over from a Scholes pass after they failed to clear.

But after 53 minutes, Redknapp’s remodelling paid off. Matt Taylor, one of two half-time substitutes, hung a cross invitingly in front of the United goal and Mwaruwari, now restored to his more familiar central-attacking role, timed his run perfectly to head powerfully past Edwin van der Sar.

“I pushed Benjani back up the middle and it gave us better balance,” Redknapp said. “It’s not systems. We just started to believe in ourselves a bit more. We tried to get in their faces. That’s what we’ve always tried to do.”

Portsmouth, though, could not afford to relax. James had to fist away a 25-yard free kick by Ronaldo and Hermann Hreidarsson blocked well after Ronaldo ran into a gap and shot from 15 yards out. But they were also now looking a more potent attacking force themselves. Mwaruwari’s fierce shot was pushed out by Van der Sar and Nugent rushed on to the loose ball, but an outstretched United foot deflected his follow-up effort over the crossbar.

Both teams were now going for the winner and United will wonder how they failed to take the lead after 71 minutes as two players contrived an astonishing double-miss. Ryan Giggs’s low cross from the right caught out the Portsmouth defence, but Nemanja Vidic, at the near post, then Scholes, at the far post, failed to make contact from a yard out.

Next, it was the turn of Tévez to fluff his lines. Allowed to run at the home defence and find Ronaldo on the right, United’s newest signing had made up yards of ground when the Portugal winger’s curling shot with the outside of his right foot was saved by James. Tévez, though, attempting to flick the loose ball home, could only put the chance wide.

After that came the flurry of cards from Steve Bennett, the referee, as a pulsating second half reached boiling point. “Muntari has just got to be careful stretching into tackles,” Redknapp said. “I didn’t even see what Ronaldo did, I haven’t got a clue. He’s not a nasty person; I can’t imagine him doing anything too bad, but the referee must have seen something.”

Portsmouth (4-1-4-1): D James — M Crainie (sub: D Traoré, 46min), N Pamarot (sub: R Hughes, 64), S Distin, H Hreidarsson — P Mendes (sub: M Taylor, 46) — B Mwaruwari, S Davis, S Muntari, J Utaka — D Nugent. Substitutes not used: J Ashdown, Kanu. Booked: Muntari, Davis. Sent off: Muntari.

Manchester United (4-4-2): E van der Sar — W Brown (sub: C Eagles, 88), R Ferdinand, N Vidic, P Evra — C Ronaldo, P Scholes, M Carrick, Nani R Giggs (sub: J O’Shea, 81), C Tévez. Substitutes not used: T Kuszczak, D Fletcher, G Piqué.— Booked: Vidic. Sent off: Ronaldo.

Referee: S Bennett.