The Jags head to Tynecastle knowing a victory, and defeat for Kilmarnock at home to St Mirren, will guarantee them a place in the Premiership next term.
Alan Archibald's side have taken five points from their first three post-split fixtures and Erskine is relishing the trip to Gorgie.
"I think you just need to be up for it when it comes to these kind of games," he said.
"I don't think the boys need any extra motivation.
"We now have two games to make ourselves safe in the top division of Scottish football - if that isn't motivation enough then I don't know what is."
Thistle return to the capital for the second successive game following their 1-1 weekend draw with Hibernian.
Despite taking a lead through Kris Doolan, the Jags failed to hold on for a crucial three points.
"I think we were sitting a bit deep and that's something the gaffer picked up on after the game," Erskine told ptfc.co.uk.
"For some strange reason teams sometimes play better when they go down to 10 men but at the end of the day we didn't press them high enough and couldn't make that extra man count."