When an 18-year-old creates Real Madrid history in a key European tie against City, it inevitably draws praise and attention.
In only his maiden start in the competition - and fifth game for the club - the young midfielder suitably impressed as the fifteen-time European champions claimed a three-nil last-16 first-leg lead at the Bernabeu.
The young player, who also had his club debut in the qualifying round a month ago with a cameo off the bench at Benfica, then helped Los Blancos overcome the English Premier League side in Tuesday's return to secure a quarter-final place.
Aged 18 years and 226 days, the midfielder became the team's most youthful starter to begin two matches in the Champions League knockout stages, beating star Vinicius Jr's previous mark by 10 days.
The midfielder is the latest to emerge from the club's academy and is quickly establishing himself as one of Alvaro Arbeloa's most promising protegees.
He signed for Madrid from CD Leganes in 2023, having previously been with Atletico Madrid and Getafe academies, and starting out for the under-19 side, where he quickly made a positive impact.
Pitarch worked his way up to the reserve side and it was during a friendly match in which they faced the academy's first team, then managed by Arbeloa, where the youngster is said to have caught the attention of the present manager, who replaced the previous coach in January.
Spanish media would later describe the moment as "an instant connection," adding he excelled not only for his technical ability, but for the vitality, character and determination he brought to the team.
In the summer of 2025, former boss Alonso invited the youngster to train with the senior squad and gave him playing time in pre-season.
Yet, it was the change in manager that became the defining moment in his career as he was introduced as a late substitute in both ties against the Portuguese side that set up the meeting with Manchester City.
"I've dreamed of this every night before going to bed, the very first time I began playing football, each day you go to train and every day you have a game," said the player following his debut.
"I have just achieved my ambition with the best team in the planet and in the top tournament."
Handed a starting debut in La Liga against his former club - where he was for several seasons after moving from Atletico in 2018 - he has kept his spot for the next four as fitness issues to Jude Bellingham and Dani Ceballos provided an opportunity.
Pitarch has seized it with displays that have defied his age and experience.
"He is a very quick player, and you can observe what he's capable of," remarked Arbeloa. "He's extremely dynamic, with excellent endurance, effort and mobility."
The player's mindset has also stood out to his manager.
"His standout trait is his personality," continued Arbeloa. "He always wants the possession, and even under pressure, he doesn't feel it.
"I realize fans might be astonished to watch him start in a Champions League match, but he's playing because I had total trust in him to perform what he usually does.
"Thiago will continue to get chances with the first team. It is delightful to have a talent like him."
Pitarch was born in Fuenlabrada, in the Madrid region, and was raised fully immersed in Spanish football, moving through youth setups before entering the club's famous La Fabrica system.
He possesses both Moroccan and Spanish nationality, giving him the option to represent both nations at the highest level.
According to Fifa eligibility rules, footballers may represent multiple nations at junior level without being permanently tied, with the final decision only binding once they appear in a official senior international match.
Pitarch has featured for Spain at youth level, turning out for both the under-19 and under-20 sides, and took part in the 2025 Youth World Cup, where La Roja reached the last eight.
Despite this, he has yet to commit to either full national side, who are watching his rise with keen attention.
In a recent interview, Pitarch said: "I haven't made my ultimate choice so far. Things are great with Spain, but I'll make a conclusion soon."
His situation mirrors that of other dual nationality players such as Real team-mate Diaz and Barcelona forward Lamine Yamal. Whereas teenage Yamal chose Spain, Diaz decided to play for the Atlas Lions.
At present, Pitarch's focus is on establishing himself in the Madrid lineup and rewarding Arbeloa's faith.
He featured for 74 minutes in the 2-1 win at City, which completed a 5-1 overall triumph and a last-eight matchup with Bayern Munich.
He was replaced by fellow youth graduate in Angel to emphasise Arbeloa's trust in the next generation to help the team chase future success.
After his impressive impact so far on European football's biggest stage, Pitarch is expected to be a central figure in that.
"Arbeloa treats me the same. We handle it very naturally. I attempt not to overanalyze it too much - I must earn my minutes on the field," he commented after the success at Etihad Stadium.
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