Sulley Muntari handed Portsmouth a shock FA Cup quarter-final win from the penalty spot to secure his side's place at the Wembley semis.

United wasted more than enough chances to win the match but manager Ferguson chose to vent his fury at Atkinson and took at swipe at Hackett, who is in charge of officials.

Ferguson felt United had a blatant penalty denied when Cristiano Ronaldo was blocked by Sylvain Distin.

"It's absolutely ridiculous," said Ferguson, whose side were denied the chance to repeat their 1999 treble success.

"I cannot explain it. Managers get sacked because of things like that and he's going to referee a game next week."

He added: "He (Hackett) is not doing his job properly and he needs to be assessed.

"I'm assessed as a manager, players are assessed, referees should be assessed properly by the right people. That performance today should not be accepted by our game."

Ferguson's assessment was echoed by winger Ronaldo who claimed he is "scared" at not being given enough protection and revealed he may change his style of play.

He said: "The referee today was unbelievable. After five minutes, there had been three fouls - but he didn't give any cards.

"Then I do not get the penalty. It's very disappointing.

"He [Distin] didn't try to take the ball; he came straight to me, and when this happens it's difficult to play football. It's a joke.

"This is the best league in the world. But I'm scared sometimes because some players do unbelievable fouls, and the referee protects the defender - not the skilled players.

"I'm thinking a lot about changing my game, because this happens. They don't give penalties, don't give yellows, don't give reds - it's difficult to play like that."

Portsmouth boss Harry Redknapp insisted Distin had done nothing wrong.

He said: "Distin is strong and used his body properly. I would have been disappointed if a penalty had been given."

Redknapp revealed the seeds of today's surprised Old Trafford win were sewn in the dressing room.

He admitted he was fearful of his side's chances after losing to United in January, while Portsmouth had not won on the ground for 51 years.

That was why he played mind games with his players in the minutes leading up to kick-off.

He said: "When I saw United's team on the notice board, I was a bit surprised because I thought they would rest Ronaldo and (Wayne) Rooney.

"I told my lads they were good players but they needed to go out and prove it. To their credit, they worked their socks off.

"We knew it would be a tough game as it was a draw no-one wanted.

"We came here a few weeks ago, lost 2-0 and it could have been 10.

"Of course we rode our luck today. You know United are going to get chances as they are a fantastic team.

"You have to take your opportunities when they present themselves."

The turning point of the game came in the 77th minute when Portsmouth were awarded a penalty after goalkeeper Tomasz Kuszczak - who had replaced Edwin van der Sar at the break - tripped Milan Baros.

Kuszczak was sent off and replaced by skipper Rio Ferdinand. However, the defender was given no chance with Muntari's cool spot-kick.

It is the third time Redknapp has enjoyed beating United in the FA Cup.

He did it first of all for minnows Bournemouth in 1984 and against with West Ham in 2001.

This is the first time the veteran boss has advanced beyond the quarter-finals but said: "I am not getting too carried away.

"I have had a number of beatings from United over the years, don't forget.

"I was hoping Sulley would just hit the target as I knew Rio at West Ham and he is not the best goalkeeper.

"It is marvellous for our supporters and the club we are going to Wembley for the semis. It will be their greatest day for years.

"It probably means more to our fans than those of Manchester United as you can get a bit blasé about these things."