Vicente del Bosque called up the 20-year-old for the world champions' friendly in Bari and the absence of the injured Xavi and Cesc Fabregas have increased his chances of winning a first cap.
"He's very young but he has demonstrated he has more than enough quality," Iniesta, scorer of Spain's winning goal in last year's World Cup final, told reporters.
"He is extremely talented considering how young he is and it is for this reason the coach has opted to call him up."
He went on to light up Barca's pre-season with goals against the likes of Bayern Munich and Manchester United, prompting debates over the need for the club to continue their multi-million euro pursuit of Arsenal captain Fabregas.
"He has these sparks that will give us a lot this season," Xavi said recently. "He has endless talent."
Thiago was born near Bari in Italy and his father is former Brazil international Mazinho, who has a World Cup winner's medal from the 1994 World Cup finals in the United States.
He joined the Barca youth system aged 14 in 2005, made his first-team debut as an 18-year-old in 2009 and possesses the touch and vision that has become the hallmark of players groomed through the club's renowned academy.
"He's in one of these moments where every time he shoots the ball goes in, but softly, softly, softly," Guardiola said on the club's Tour of the United States.
"All types of excess are bad. He is very young, has a lot of ability, but still has a lot of room for improvement."
