Three days after beating Santa Fe with a dramatic late winner to secure a spot in the final, Tolima faced their next big task at their own Manuel Murillo Toro stadium in Ibague.
Things started well for visiting side Once Caldas as Dayro Moreno scored the opening goal after just seven minutes.
But an own goal from defender Alexis Henriquez restored the balance in the 35th minute and the home team were handed a penalty shortly after the break. Rodrigo Marangoni remained calm and scored from the spot.
There was more bad news for Once Caldas as Diego Arias was sent off with a red card in the 74th minute and will miss the return leg of the final.
That return leg will be played in Manizales on Sunday, with kick-off time set at 5:30pm local time.