Liverpool escaped with a fortunate draw after a poor display against Porto in this Champions League Group A match.
Liverpool goalkeeper Jose Reina gave away a penalty and was beaten by Lucho Gonzalez's spot-kick on eight minutes.
Despite their error-strewn first-half performance, Dirk Kuyt pulled Liverpool level with a close-range header.
But Liverpool had to play with 10 men for over 30 minutes of the second half after Jermaine Pennant was sent off after picking up a second yellow card.
If Liverpool are to reach their third Champions League final in four years they will have to cut out the mistakes that littered their play in the first half.
Too many Liverpool players were too ponderous and too often the visitors conceded possession too easily.
In Ricardo Quaresma, Porto had a player all too eager to capitalise on Liverpool's mistakes.
Unfortunately for the Portuguese champions had nobody to finish off Quaresma's impressive approach work.
Quaresma gave Steve Finnan and Pennant all sorts of problems on the right for Liverpool as they tried to keep track of the tricky Porto winger.
Pennant was booked for a first-half tackle on Quaresma and the former Arsenal winger was sent off just before the hour when he foolishly fouled Lucile.
Trying to chase a Javier Mascherano pass, Pennant swung wildly as the Uruguayan shielded the ball.
A pointless challenge that ensured Pennant's deserved dismissal.
Strangely Liverpool looked more cohesive at a numerical disadvantage and apart for a half-chance for Quaresma the final 30 minutes passed without too many scares for the visitors.
Late on Quaresma had track back to his own penalty area to ensure Kuyt did not reach Steven Gerrard's dangerous pass.
The first 10 minutes must have been akin to a horror movie for Liverpool's perfectionist manager Rafael Benitez.
Finnan was too slow in trying to clear his lines and after he was tackled by Quaresma the ball richocheted to Lisandro Lopez.
The Porto striker had just Reina to beat, but the Spanish keeper did well to block Lopez's shot.
Carragher was the next Liverpool defender to fail to clear, enabling Quaresma to send in a shot that just went over the bar.
Liverpool might have escaped on those two occassions, but there was to be no repreive when a third mistake was made.
Tarik Sektioui was too quick for Sami Hyypia and then for Reina as the Moroccan went down under the challenge of the Liverpool goalkeeper.
Reina's record of saving penalties is superb, but he was fooled by Gonzalez as the Argentine midfielder put his shot in the centre of the goal as the Spanish keeper dived to his right.
If Finnan and Hyypia had had less than impressive starts the two Liverpool defenders were soon to made amends.
Finnan's diagonal free-kick was headed across the goal by Hyypia and Kuyt beat Nuno with a close-range header