The 13.19 (97) to 11.6 (72) defeat at the club’s International Football Festival in front of more than 5000 spectators made it four straight defeats for the Falcons at home.
West Perth has struggled at Arena in 2014, having won just two of eight home games for the season, its last Joondalup victory coming two months ago against Peel.
The Falcons suffered a major goal drought through the middle of the match, allowing the third-placed Lions to jump to a 46-point lead.
Teenage forward Matt Johnson broke the goalless run 18-minutes into the third quarter, before a surge of four-straight majors from West Perth gave the side a glimmer of hope 28-points down at three-quarter time.
The Falcons won the final quarter 3.2 to 2.5 but it was not enough to make up for their earlier lapse.
Working in fifth-placed West Perth’s favour was East Perth defeating fourth-placed East Fremantle to keep the reigning premiers’ top-four deficit at three games.
But the Falcons are likely to be four wins outside the final cut with a game in hand after their bye this weekend with the Sharks facing bottom-of-the-ladder Peel.