The tactician refuted claims that the Barcelona player only received a call-up because he is eligible for the South Americans, and looks forward to his side's clash against Italy
The midfielder is eligible to play for the five-time World Cup winners as a result of Fifa's parent ruling as Thiago's father, Mazinho, is from the South American country.
However, the ex-Real Madrid coach maintains that it is his fine form displayed over the summer that is the reason behind his call-up - and not the fear that Brazil might poach the youngster first.
"Thiago has the option of choosing which team he wants to play for," Del Bosque explained to Marca. ''He is in the squad due to sporting merit."
However the 60-year-old acknowledged that a player of Thiago's quality should have been in the Brazil squad already, such is the high regard in which he holds the youngster.
"There are players, who for his [Thiago's] career achievements, should be in the Brazil squad.
"We do not look at the status of each player, we look at their quality. Right now, I've got a lot of confidence in the likes of Thiago."
Del Bosque also went on to praise the state of his nation's football, who are winning almost every international tournament there is at the moment.
Since Spain won the World Cup last summer, their youngsters have enjoyed similar success as earlier in the summer both their Under-19 and Under-21 teams won their respective Uefa European Championships.
"We are all very pleased with the current situation of football from top to bottom in this country. This is the best time in our history."
Finally, the experienced Spaniard spared a few words for his teams opponents next week. Spain take on Italy in a friendly encounter next Wednesday in Bari and Del Bosque is looking forward to the clash between the last two World Cup-winning countries.
"The goal of this game will be to compete with a strong Italian team. They [Italy] have been world champions recently  and it will be great preparation for the players. They are a world class rival for us and are one of Europe's best teams."