Having replaced the injured Helder Postiga during Portugal's 1-0 quarter-final win over the Czech Republic, Almeida revealed on Tuesday that he has been awarded a starting berth in coach Paulo Bento's line-up.
"Yes, I'm happy," he said. "I've worked a lot to be included in the starting line-up and I intend to take this opportunity. I was always motivated, like all the 23 players in the squad. We were selected to be in the squad and we all want to play.
"Of course I was a bit sad not to be in the starting line-up, but I'll do everything to help my team," he added. "You have to work from day to day and be prepared to show your very best on the pitch when the opportunity comes."
With Portugal likely to have to defend for long periods against the reigning world and European champions, Almeida knows he will need to make the most of any goalscoring opportunities that come his way.
"We have to score," said the 28-year-old Besiktas striker. "That's our first aim. We know Spain have great quality and incredible players, but we have to keep working and do everything we can to score."
Almeida will be flanked in the Portuguese attack by Cristiano Ronaldo, whose glittering displays against the Netherlands and the Czechs played a decisive part in sending Portugal into the last four. "Playing with Cristiano is a great pleasure," said Almeida.
"I'm proud to play with one of the best players in the world. He has a great personality and I know he'll do everything to lead Portugal into the final, just like the other 22 players in the squad," he went on.
After emerging from a group containing Germany, the Netherlands and Denmark before edging the Czechs, Portugal now stand on the verge of reaching a major final for only the second time in their history. Almeida was not a member of the squad that fell to Greece as hosts in the final of EURO 2004, but he says he is desperate to make his mark with the national side.
"It would be a great dream and I would be very proud, as well as my team-mates," he said when asked what it would mean to reach the final. "Now we're in the semi-final and we have to get past Spain, who are world and European champions with great pedigree in the team. We will do everything to reach the final."