[2] During his student years he won the world university championships in Darmstadt where he defeated Fritz Kuhlmann without losing a set.
[2] It took him several years to repeat his first feat when in 1926 he won the tournament Parc des Eaux Vives in Geneva against Swiss champion Charles Aeschlimann.
[17] In 1931 he became Libyan Champion by beating fellow countryman Alberto Del Bono in the Tripoli final and won the doubles title partnering with him.
[23] In 1933 he was a challenger for another Montreux title but finished second against Gottfried von Cramm but [24] did win the doubles trophy against the German duo Cramm-Lund.
[28] In 1934 he was the finalist for both singles and doubles at the Italian Internationals losing both times to Davis Cup teammate Giovanni Palmieri.
8 in Europe in 1931 according to the Züricher Sport newspaper[35] and reached the same rank in 1935 on the list of Heinrich Kleinschroth, a former German champion and Davis Cup player.
[36] De Stefani finished runner-up to Henri Cochet in the singles final of the Amateur French Championships of Roland-Garros in 1932.
[39] In their 1932 Pacific Southwest Tournament semifinals rematch Perry equalized their tally and went on to face Jiro Sato for the title.
[40] In their third encounter in the 1933 International Lawn Tennis Challenge where Great Britain defeated Italy with Stefani winning the only rubber of that quarterfinal.
He wanted to lose as a noble thus offering his Italian opponent "an honourable victory" if they avoid long, wide rallies that would damage his ankle more.
[42][44] Thus in return, on their next match-up in the quarterfinal of the Australian Championships in Melbourne Perry crushed the Italian, ruining his best oversees result and giving him the biggest loss of his life with a score of 6–0, 6–0, 6–0.
[1] As an attempt to reorganize the Italian sports life count Alberto Bonacossa[1] offered him the position of Regent of the Presidential Committee of tennis, which Stefani accepted and held in 1943, however as Italy's war involvement escalated, it forced him to leave his office.
[1] He surrendered to General Harold Alexander with the aid of the partisans, who helped him to make contact with the English forces.
[1] De Stefani later became a sports official, was invited and elected in August 1951 on the International Olympic Committee (IOC).
[1][51] In 1966 he initiated the reintroduction of tennis at the Summer Olympics at the IOC meeting in Melbourne and eventually succeeded when eleven votes had been discarded.
The President of the IOC, oppositional Avery Brundage protested to the outcome and demanded a new voting process due to fabricated technical errors made in the previous one.
[54] Allegedly he even convinced Italian number one Nicola Pietrangeli with financial means to devote himself exclusively to amateur tennis and never turn professional.
[51] Giorgio de Stefani was an ambidextrous player, which allowed him to switch his racquet from one hand to another to always return a forehand shot.
[43] In one of his articles written to The Sydney Morning Herald, Fred Perry described Stefani as a "freak player" and his style as unorthodox and that he lacks the beauty of shot execution of those as Bunny Austin and Jack Crawford.
[59] His uncle was the politician Alberto De Stefani, who was the Minister of Finance, but was removed by Benito Mussolini due to their ideological differences.