I don't think it's under-stating it to say the wheels are coming off - you've got be worried about Manchester United.
If it was a one-off performance, I would turn round and question anybody saying that.
After what the boss said after the Inter game, he was disappointed in the way they performed but they got through and a few people said you shouldn't be worried, it's just about getting through.
There was a method in Sir Alex Ferguson's madness because you saw the performance against Liverpool was quickly followed by a poor 45 minutes against Fulham. You thought, right they've got that out of the way and then came Aston Villa. That wasn't good and they got through by the skin of their teeth.
In the first 20 minutes last night, what Porto did was their homework. They thought we're going to go there to Manchester United and gamble and ask questions. United did not respond.
If Porto had walked in 2-0 or 3-0 up at half time, nobody would have been surprised at Old Trafford.
To be honest, the clean sheet run was on the back of different people partnering Nemanja Vidic. Jonny Evans came in if Rio Ferdinand was out and it wasn't the consistent back four you expect to see.
You still expect players of that calibre at Manchester United to be able to sort that out but you have to remember Edwin van der Sar only had about 20 shots during that run. He's had 26 shots in the last four or five games.
The difference is teams are having a go at Manchester United's back four. If you don't have a go, anybody can keep a clean sheet. Teams are coming out and actually expressing themselves and just saying we've got nothing to lose.
They are causing problems and scoring goals and that is what football is all about. If you don't try, you don't get anything.
Normally, when teams like Porto do attack United at Old Trafford, their supremacy in the Champions League has been so strong and their manager would have been saying watch out for the counter-attacks.
There were no counter-attacks. The defence wasn't doing its job as such and the midfield wasn't doing its job in helping shield the back four. When they did win the ball, they couldn't spread the ball because they were too far back.
Cristiano Ronaldo was not doing enough in the right areas and they could not get the ball forward quickly enough. So Porto were playing like the home side and were dominant everywhere.
United started the second half better but still didn't have enough ideas to really break Porto down. The visitors should be a little disappointed to go away conceding two goals and finishing at 2-2.
I don't want to say it but it worries me that no British side has gone and won in Porto's new stadium.
I was there and I've not seen a side go to Old Trafford like that - I've seen them go there and have a good go but United have come on strong - but never been that consistent in that expressive way of playing for so long at Old Trafford.
At this moment in time, given what I've seen, I've got to go with Porto to get through at the moment.