Australian surfer Reef Heazlewood finished the heat in fourth place with 9.30.
The Cascais competition is one of five top events on the QS offering the winner 10,000 points towards CT qualification.
It has attracted a huge contingent of CT surfers facing elimination for next year’s CT.
Only the top 22 ranked surfers on the CT are guaranteed qualification for the next year and the only other avenue is to finish in the top 10 on the QS.
Christie sits in 15th place on the QS with 10,650 points but will need to finish the year in the top 10 (at least 20,000 points) to requalify for the top-tier Championship Tour (CT).
Christie has done well in the powerful beachbreaks of Cascais in the past, with a third placing in 2014 contributing to his qualification for the 2015 CT.
In Round 3 he will be up against Noe Mar McGonagle of Costa Rica, 12th-placed QS surfer Wade Carmichael of Australia, and Brazilian Italo Ferreira, who is in 23rd place on the CT.
Christie will likely surf tonight (NZ time) with a new swell filling in.