The Harbour City side, who are battling relegation, picked only one win in their last four games and did not claim win in their last two away games.
"The game against Hearts won't be easy but we believe in ourselves and hope things will work for us to take the three points at stake," Paintsil told Goal.
"Accra Sports Stadium is an open ground for any team and if you know how to play good football, winning there is easy especially if you are with them in the same city. We stay with them and know whatever they have including their weaknesses so Tema Youth will shock them."
He added: "We need to survive relegation and cannot afford to lose this game. Our survival depends heavily on this game because those we're battling with are playing home games and will likely win. We need a bit of luck too on Sunday but I assure our supporters of good results."
Tema Youth sit 12th position on the log with 28 points, two points above the drop zone.