And his gaffer has criticised the action of referee Maurizio Mariani on his decisions in the encounter.
“I would’ve liked to play this game 11 against 11 to the end,” Mazzarri told DAZN.
“This was played in a passionate atmosphere with fiery fans. I thought Nkoulou had been fouled first, then he was forced to recover, but it was originally Alberto Paloschi’s foul.
“There was also a foul on Andrea Belotti that was turned into a free kick against him. We could even have won it with Daniele Baselli. I am a little angry, as I wanted to use my substitutions differently to introduce quality towards the end.
“We were up against a SPAL side that had nothing to lose, but the lads were ready for it.”
Nkoulou has played a key role in helping Torino keep eight clean sheets in his 22 league appearances this season.
The Bull are tenth in the log with 31 points from 22 games. They will hope to bounce back to winning ways when they trade tackle with Udinese on February 10.