[4] Langenus was selected to officiate at the 1928 Summer Olympics, and he refereed the first round match on 30 May 1928 at the Olympisch Stadion, where Uruguay beat the Netherlands by 2–0 in front of 40,000 people, and confirmed their place in the quarter-finals.

[7] Two "Group" matches played under his stewardship were followed by the first semi-final between Argentina and the United States on 26 July 1930, which finished 6–1 to the South American side.

The home country Uruguay met Argentina, and feelings were running high even before the match; the "big, tough, ruthless centre half"[10] "Argentinian Luis Monti received a death threat" and the referee "demanded a quick escape route plan to get back to his ship".

[16] On 19 June 1938, at the Parc de Lescure in Bordeaux, Langenus received his second great career honour, having been chosen to oversee the third place playoff between Brazil and Sweden.

[17] By resting their tournament top scorer, Leônidas, in the semi-final, Brazil may have caused their own eventual participation in the lesser match instead of gracing the Final as expected.