The Cascais competition was one of five top events on the World Surf League Qualifying Series (QS) offering the winner 10,000 points towards CT 2018 qualification.
Christie sat in 15th place on the QS with 10,650 points before the competition but will likely slide down the rankings following his early exit from this competition.
He needs to finish the year in the top 10 (at least 20,000 points) to requalify for the Championship Tour.
He can qualify from outside the top 10, but only if surfers above him also qualify by way of the CT.
The next big competition on the QS is the Hawaiian Pro at Haleiwa, Oahu, Hawaii, starting on November 12.