The Rhinos, who have rediscovered their form too late to climb out of the bottom four, knocked Hull off the top of the Super League table a week ago but helped them reclaim the spot by defeating their nearest rivals in a tense Grand Final re-match at Headingley.
The reigning champions looked to have the game sewn up when they led 18-4 after 65 minutes but they were forced to withstand a late rally from their visitors before clinching an 18-16 victory that lifts them off the bottom of the table.
England centre Kallum Watkins was back to his best and halfbacks Jordan Lilley and Rob Burrow sparkled for Leeds.
But it is the recent addition of Segeyaro, who made his home debut, that has finally made the Rhinos a more rounded team.
Segeyaro fell out of favour with Penrith coach Anthony Griffin and the 2014 Dally M Hooker of the Year signed a two-year deal with Leeds last month in a trade that saw Rhinos fullback Zak Hardaker switch to the Panthers.
Wigan, who gave a debut to new signing Frank Paul Nuuausala for his first game for three months, had nine senior players missing through injury or suspension but played their full part in a rousing encounter in front of a 16,712 crowd.
Salford head coach Ian Watson praised winger Mason Caton-Brown after his hat-trick helped the Red Devils beat Widnes 32-24.
Caton-Brown only recently returned to action following an ankle operation and had scored only one try this season before his match-winning treble helped Salford secure their second win in six games.
Watson, whose side are resigned to playing in the Qualifiers, said: "Mason's speed caused Widnes all sorts of problems. He was brilliant."
Picture: Former Penrith Panther James Segeyaro with the Leeds Rhinos: Picture credit: Robb Cox NRL Photos