Parramatta are well poised for a late-season charge to the NRL top four after spoiling Benji Marshall's party with a 30-18 victory.
Tigers veteran playmaker Marshall became the 38th player in league history to reach the 300-game mark on Sunday at Bankwest Stadium, however his side failed to do the occasion justice.
Mitchell Moses, playing against his former club, was superb, setting up two tries and booting seven goals from seven attempts - including several difficult shots from the sideline.
Both sides scored four tries but Tigers pair Esan Marsters and Moses Mbye missed three of their four attempts with Moses' boot proving the difference.
"He's kicking and playing with a bit of confidence," Eels coach Brad Arthur said.
"A couple of those kicks early were kicks that he needed to make. But the timing of them and the mentality of taking those shots was probably more pleasing than anything. He kicked a couple of pressure kicks."
Centre Brad Takairangi finished with a hat-trick of tries as the Eels jumped into sixth spot on 20 points, giving them a six-point buffer over ninth-placed Cronulla.
Asked when his side could start thinking about finals, Arthur said: "When I know we're going to be reliable, week in and week out - when we know we've got 17 blokes that can rely upon each other."
The damage was done in the 10 minutes before halftime with Takairangi running in back-to-back tries from consecutive sets which gave his team a 16-4 lead at the break.
Takairangi's first came in the 33rd minute after Parramatta were controversially handed possession when Luke Brooks was ruled to have knocked on after Blake Ferguson had flung the ball in-field.
Replays suggested Ferguson's body went into touch but the Eels retained possession and capitalised on the opportunity.
The Tigers' handling was woeful in the first half, completing just 10 of 16 sets, and the first time they ventured into the Eels' red zone after halftime, they converted it into points via David Nofoaluma.
The Tigers looked like they were set to get back within two points when Corey Thompson reeled in a Nofoaluma grubber but he was ruled offside, only for the Eels to run upfield and score via Ferguson.
The Tigers were punished after losing the penalty count 7-4 and committing nine errors to the Eels' six as they suffered their second-successive loss.
The Eels had five forwards run for 100-plus metres - including standout Nathan Brown (140m, 27 tackles) - while Thomas Mikaele was the only Tigers' forward to cross the mark.
"We've got a bit to work on," coach Michael Maguire said.
"One thing I know about the group is they try.
"At times, we just need to be more diligent around certain areas of our game.
"We had a lot of errors, we didn't apply pressure and, unfortunately, that puts pressure on yourself.
"If you're going to keep doing that, you end up where we did on the scoreboard. We need to have a look at ourselves."