The talented youngster was rewarded for his form at Anfield with a cap in his side's 3-1 win over Italy on Wednesday, and already described this campaign as an 'amazing season'
The 18-year-old has impressed for Brendan Rodgers' side despite the club lingering in 13th position in the Premier League, and signed a long-term contract in October.
And the winger has taken the next step in his international career by featuring in his national youth side's 3-1 victory over the French, and vowed to keep working hard to improve as a player.
"Another dream becomes true. Made my debut for Spain U21. Can't be happier and what a amazing season this one. Now keep working hard. Thank you all," the Spaniard tweeted.
Suso was delighted to sign a new deal at Anfield, suggesting he believes he is at the right club in order to develop his talents
Speaking to the club's official website, he said: "Liverpool are one of the biggest clubs in the world and this is the right place for me.
"I am comfortable here. I have played some games for the first team and I hope to continue doing that, but I need to work hard every day for that to happen."
Rodgers was also pleased to secure the services of the promising player, saying: "At 18, [Suso] has demonstrated outstanding technical qualities but also shown very good temperament to play for such a prestigious club."