Poor finishing dogged Portugal for much of their World Cup qualifying campaign and they only qualified for the June 11- July 11 finals in South Africa after a play-off victory over Bosnia.
Portugal are in the Group G with Brazil, African heavyweights Ivory Coast and North Korea and will have to be much more clinical in front of goal than they were on Wednesday if they are to avoid an early exit.
The hosts dominated the first half, but were only able to produce the one goal, through Almeida following a counter attack before Liedson, who had replaced Cristiano Ronaldo at half time, deflected in a Joao Moutinho shot deep into injury time.
Portugal coach Carlos Queiroz had chosen to play China as preparation for their World Cup match against North Korea on June 21, and the team welcomed the return of Ronaldo, who had missed the two-legged playoff victory with an ankle injury.
With playmaker Deco injured, Queiroz used Almeida up front with Simao Sabrosa sitting behind him and Nani and Ronaldo on the wings.
The quartet tormented the Chinese defence throughout the first half though they also failed to convert several chances.
Nani sent a volley and a header wide in the first 15 minutes before Almeida forced keeper Zhang Lu to a tight save on 18 minutes and then had a header cleared off the line by Rong Hao.
Portugal's opener came on the counter when Ronaldo chased a loose ball from China's first corner, galloped ahead and passed for Almeida to fire in unchallenged to give the hosts a 1-0 lead at the break.
Queiroz made five changes at halftime, including replacing Ronaldo with Liedson, and with several of the replacements playing out of position his side failed to gel or maintain the tempo of the first half.
Portugal's best second half chance came in the 65th minute when debutant Silvestre Varela's cross was met by a thunderous Raul Meireles shot that hit the post.
China, the East Asian champions, had two half chances in the final 10 minutes, which caused the home fans to voice their disapproval and Portugal's second goal in injury time failed to appease the fans' worries.
