The West Lothian club must win at McDiarmid Park to leapfrog Saints and stay in contention for European football next season.
Martindale admits that game was already on his mind when he picked the team which lost 3-0 at home to champions Rangers on Wednesday evening.
“I made a couple of changes and tried to get boys off the park because I want to have options on Saturday,” said Martindale.
“It’s a big game for us and it’s difficult with only a 48 hour turnaround hence why big Marvin Bartley, for example, never started against Rangers.
“It’s not payback for the cup final defeat against St Johnstone because you want to win every game. But it will be part of my team talk.”
Martindale felt the concession of the penalty just before half-time, when his goalkeeper Max Stryjek fouled Ianis Hagi, was the pivotal moment against Rangers. But he was pleased by aspects of his team’s performance, if frustrated by the chances they missed.
“I’m disappointed to lose the first goal at that stage because there wasn’t much in the game,” he said.
“I’ve not seen the penalty back but I don’t know if the goalie should maybe do a bit better – he came out and tried to use his body when he could have used his hands.
“Hagi has got the first contact on the ball and has done really well. So for me it’s a penalty.
“You go in 1-0 down then you lose a second and we came into the game a bit. I thought the substitutions worked and gave us a but more impetus.
“Wee Jaze Kabia has hit the post – he’s in the right position – but he’s got to score in my opinion. If that goes in then it’s probably a different game.
“We made enough chances to score and change the dynamics of the game.
“But Rangers are on this unbeaten run and have this incredible number of clean sheets.”