After a two-match losing streak, Ferguson must have felt United were back on the march again with their last-minute winner against Aston Villa last weekend.

Yet only 48 hours later they found their Champions League defence hanging by a thread following Porto's late equaliser at Old Trafford.

Most pundits felt the Red Devils looked jaded, a situation unlikely to change ahead of next Wednesday's second leg given the number of injuries Ferguson's side are carrying.

However, the United boss does not believe the evidence backs up such a theory. All he feels the Old Trafford outfit need is a more solid defence.

"Some people said we looked tired on Tuesday," said Ferguson. "We looked tired in the first half and were short of sharpness and rhythm in our game.

"But we did well in the second. There is nothing wrong there. We just have to stop these silly goals."

Conceding soft goals is a virus that dates back to the home defeat by Liverpool a month ago.

In the four games from that point, Edwin van der Sar has been beaten 10 times - the same number of goals United had conceded in the previous 22 matches.

Particularly galling was Porto's late equaliser on Tuesday after Wayne Rooney had dragged his team-mates back into a game they trailed from the opening minutes.

"There is a watershed for everything," said Ferguson. "Hopefully we reached it on Tuesday night because that late goal was a real kick in the teeth."

At least, after playing two games in three days, United have had more time to prepare for Saturday's trip to Sunderland.

They also have a four-day preparation for the return leg against Porto and equal time to get themselves sorted for Sunday's FA Cup semi-final with Everton at Wembley.

"The spacing of our games has been terrible," said Ferguson. "I have to hold my hands up because we did not give the players the best preparation for Tuesday. But we were stuck between the devil and the deep blue sea.

"We had the option of playing on Saturday lunchtime, which was not the best in terms of preparation for Villa. But playing on Sunday was not the best for Tuesday. We have been caught in that way."

The one consolation Ferguson can draw from a difficult period is his side managed to avoid defeat.

By common agreement, Villa and Porto dominated the first half of both games. Yet United emerged with a win that kept their noses in front of Liverpool in the Premier League and a draw that gives them some chance of progressing to the Champions League semi-finals for the third successive year.

"If you don't have character, you get yourself into situations where you might find yourself wanting," said Ferguson.

"Fortunately there is a good competitive nature at this club.

"The fact we have been winning for the last few seasons gives them an in-born character to try and get out of the situation they found themselves in last Sunday.