When an teenage makes club history in a key European tie against Manchester City, it inevitably draws acclaim and the spotlight.
In only his maiden start in the competition - and fifth appearance for the team - the young midfielder made a strong impression as the fifteen-time European champions secured a 3-0 round of 16 first leg advantage at the Bernabeu.
The teenager, who also made his Real debut in the play-off round a month ago with a substitute appearance at Sporting Lisbon, then helped Los Blancos overcome the English Premier League side in Tuesday's return to confirm a last eight place.
At 18 years old, Pitarch was the club's most youthful starter to start twice in the Champions League knockout stages, beating Brazil forward Vini Jr's previous mark by a week and a half.
The midfielder is the latest to emerge from the club's academy and is quickly establishing himself as one of the manager's most exciting young players.
He joined Madrid from Leganes in 2023, having previously been with Atletico and Getafe youth teams, and initially featuring for the Juvenil C team, where he quickly made a strong impression.
Pitarch worked his way up to the B team and it was in a pre-season game in which they faced the academy's first team, then coached by the former defender, where the youngster is said to have drawn the eye of the current Real boss, who took over from Xabi Alonso in the new year.
Spanish media would later label the moment as "love at first sight," adding he excelled not only for his technical ability, but for the energy, character and determination he added to the team.
During the pre-season of 2025, ex-manager Xabi Alonso called up Pitarch to train with the senior squad and gave him minutes in pre-season.
Yet, it was the change in manager that became the defining moment in his career as he was introduced as a second-half replacement in both ties against the Portuguese side that led to the clash with Pep Guardiola's team.
"I have dreamed of this every night when sleeping, the very first time I started playing the game, each day you go to train and every day you play a match," said the player after his debut.
"I have just achieved my ambition with the greatest club in the planet and in the best competition."
Handed a starting debut in La Liga against his former club - where he was for several seasons after arriving from Atletico in 2018 - he has retained his spot for the following four as fitness issues to Bellingham and Dani Ceballos created an opening.
The teenager has seized it with displays that have belied his youth and inexperience.
"He is a extremely fast footballer, and you can observe what he's capable of," said Arbeloa. "He's incredibly dynamic, with great endurance, work-rate and movement."
Pitarch's mentality has also stood out to his coach.
"His standout trait is his character," added he. "He constantly demands the ball, and even under pressure, he doesn't feel it.
"I realize fans might be surprised to see him make his debut in a European fixture, but he is selected because I had complete trust in him to do his normal game.
"Thiago will continue to get opportunities with the main squad. It is delightful to coach a talent like him."
Born in a Madrid suburb, in the Madrid region, and grew up fully immersed in Spanish football, moving through youth setups before entering the club's famous La Fabrica system.
He holds both Moroccan and Spanish citizenship, giving him the option to represent both nations at senior international level.
Under international regulations, players may represent multiple nations at youth level without being locked in, with the ultimate choice only final once they play in a competitive senior international match.
He has featured for the Spanish national team at youth level, turning out for both the U19 and under-20 sides, and took part in the 2025 Youth World Cup, where Spain reached the last eight.
Nevertheless, he has not yet decided to any full national side, who are watching his progress with interest.
Speaking recently, Pitarch said: "I have not taken my ultimate choice so far. Things are positive with the Spanish federation, but I will reach a decision soon."
This scenario mirrors that of other bi-national players such as Real team-mate Brahim Diaz and Barcelona forward Yamal. While 18-year-old Yamal chose La Roja, Diaz opted to represent Morocco.
For now, Pitarch's focus is on making his mark in the Madrid lineup and rewarding his manager's belief.
He played over an hour in the two-one victory at City, which sealed a five-one aggregate success and a quarter-final tie with the German champions.
His substitution by fellow youth graduate in Manuel Angel to emphasise Arbeloa's trust in younger players to aid the club pursue future success.
Following his impressive impact so far on the Champions League, Pitarch is expected to play a key role in that.
"Arbeloa handles me the identical way. We handle it very naturally. I try not to overanalyze it excessively - I have to earn my minutes on the field," he said following the success at Etihad Stadium.
Mira is a tech journalist and AI researcher with over a decade of experience covering emerging technologies and their societal impacts.