Rafael Benitez's winning start as Liverpool manager came to an end with a 1-0 defeat against Porto in Toronto.
Carlos Alberto was on target for Porto
Liverpool had looked set for a draw but Carlos Alberto scored in the 85th minute for the European champions after being left unmarked in front of goal
The Reds had their chances with Michael Owen twice going close with headers in the first half.
Their third and final game in North America comes against AS Roma in New Jersey on Tuesday.
Porto, under new coach Luigi del Neri, looked shaky at the back at the start as both Owen and Djibril Cisse caused them some nervous moments.
But the Portuguese side eventually woke up and Ricardo Quaresma hit the crossbar while Benni McCarthy also came close.
Quaresma then hit the upright in the 29th minute, sparking a goalmouth scramble, but Porto could not turn the ball in.
Both managers made changes at the break and Benitez swapped Owen and Cisse for Milan Baros and Florent Sinama-Pongolle in attack.
The Portuguese side threatened first after the break when Quaresma forced a good save out of Dudek.
Porto's tactics were frustrating Liverpool with Kewell getting a yellow card after kicking out at an opponent while Pongolle was also booked for lashing out at Rossato.
But Porto saved the best until last, taking the lead with just five minutes remaining.
The Liverpool defence were stretched as Areias' cross was allowed to come to Carlos Alberto at the back post and he had the easiest of tap-ins with Dudek