Laurentz achieved his breakthrough in April 1911 at age 16 when he defeated the Wimbledon champion Anthony Wilding in the final of the French Covered Court Championships in Paris.

[1] In March 1912 he was playing in the Challenge Round of the Championship of France against Andre Gobert when at 2–4 in the first set a ball that glanced off his racket struck him in the eye.

In the final of the latter, played on clay courts at the Stade Français in Paris, he beat Andre Gobert in four sets.

[4] In 1921 he won the singles title at the World Covered Court Championships (WCCC), played in Copenhagen on an indoor wood surface, beating Alfred Beamish in the final in straight sets.

Laurentz participated at the Wimbledon Championships for the first time in 1919, losing in straight sets in the first round to Algernon Kingscote.