In his first NRL game for the best part of three months, halfback Jonah Pezet scored the decisive try and added a nonchalant field goal as the youthful Eels claimed their sixth - and arguably most impressive - win of the campaign.
But even if Jason Ryles' side were without captain Mitchell Moses and forward leader Junior Paulo the focus will be on Manly, who have hit a patchy run of form.
The Sea Eagles' fans christened their resurgence under Foran 'Fozball' after he won seven of his first eight games in charge to earn a long-term extension.
But Manly have now picked up three wins from their past six outings and slumped to seventh with defeat to the Eels.
"It was a tough watch and we were way off with the ball and the inconsistency in our performances at the moment is something we need to fix," said Foran, whose side are now two wins outside the top four.
"It's my job to work that out, but I haven't loved what I've seen the last six weeks, in terms of up one week down, the next we're up.
"We completed at 93 per cent last week against Melbourne, and then we came out today and completed at 65 per cent. You just can't win games of footy doing that.
"You don't need talent to hold the footy, you don't need talent to get through your sets and I thought we just disrespected the footy.
"We didn't want to get through our sets and didn't want to play the long grindy game.
"It was all self inflicted."
Manly led 8-6 at halftime as a result of two penalties from Jamal Fogarty and a Lehi Hopoate try after lively Eels five-eighth Ronald Volkman darted over for the opener.
But the Sea Eagles made 17 errors, 11 of them in the second half, and the Eels were good enough to take advantage of their wastefulness.
Dylan Walker provided an assist of the year contender for Kelma Tuilagi to push the Eels ahead.
And while Joey Walsh pulled one back for Manly, the home side were too strong with Isaiah Iongi and Pezet crossing - before the half added a late one-pointer - to seal victory.
"He (Walker) has been practising a flick pass at training and I didn't think in 1000 years it would ever come off so we're in for a long week in regards to hearing about it," said Ryles, whose side climbed above Brisbane into 14th spot.
"We gave ourselves some opportunities, which we bombed, but then we found a way to hang in and then we ended up taking them."
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