The 26-year-old is on a season-long loan from Thai Premier League side Muangthong United as he bids to seal a permanent deal with the Spanish side, who narrowly avoided relegation last term after finishing one point above the drop zone.
"I was already happy when I was named one of the substitutes for the match. I'm delighted to see action on the pitch. I can't describe my feelings," Teerasil was quoted as saying by Thai media on Monday.
"I didn't know whether I was delighted, excited or nervous. It's a mixture of all but mostly it's one of satisfaction to get a taste of what we previously could only watch on television."
Teerasil had a brief spell at Spanish champions Atletico Madrid last year but did not play in the first team.
He also had a trial at Manchester City in 2007, when the club was owned by his compatriot Thaksin Shinawatra, but was unable to gain a work permit and left without playing.
Teerasil, a mainstay of the national team, said it was too soon to say whether the Almeria deal could become permanent.
"Let's see how it turns out. It's only one match so we cannot tell anything," he added.
"There are still many things that I need to work on if I want to make more appearances or break into the first team. I need to improve on many things."
- Sports & Recreation
- Thai Premier League
- Muangthong United