Green played the full 90 minutes as the Pilgrims won 2-1 at Aggborough Stadium to set up a semi-final trip to AFC Fylde on Sunday.
Earlier this week Rovers confirmed Green’s appointment as youth development phase transition coach with the academy which will involve working with players in the under 16s and under 18s.
But he is still having a big impact on the pitch and is hoping to help Boston, who have close ties with Rovers, reach the National League.
“Paul’s been very influential for United this year, both on and off the pitch,” said Duncan Browne, who covers Boston United for LincolnshireWorld.
“He was the engine room in last night's play-off win and it was one of his best performances for Boston.
“He struggled to get a start at beginning of the season under Craig Elliott – his boyhood pal from Pontefract – but managed to become a regular.
“A couple of injuries set him back, most notably a shoulder injury he picked up in his last game as player-caretaker manager at Spennymoor in January.
“He only came back for the last four games but has been immense.”
Green has scored two goals in 24 appearances for Boston this season.
He made over 200 appearances for Rovers between 2002 and 2008 as the club rocketed up the leagues from the Conference to the Championship.
The former Republic of Ireland international returned to Rovers last year as a part time fitness coach under former teammate Richie Wellens but left in January to briefly take interim charge of Boston.
Boston train in Doncaster on the 4G pitch at the Eco-Power Stadium having relocated there in 2019.
Former Rovers defender and interim manager Andy Butler signed for the Pilgrims last summer but played only one County Cup game before leaving to take up a coaching position at Peterborough United.
Current Rovers boss Gary McSheffrey also played one County Cup game for United in 2018.