Rodrigo Lopez's late equaliser helped Libertad salvage a point at home to 3 de Febrero, earning a 1-1 draw on Monday.
Pedro Sarabia's men remain top of the table, but their lead has been cut to two points and Cerro Porteno have played one fewer game.
But Libertad looked set for a loss when Amaral put visiting 3 de Febrero ahead in the 61st minute.
Lopez levelled with seven minutes remaining to ensure his side remain in a decent position to win the Clausura.
Cerro Porteno had put the pressure on the leaders a day earlier, beating 12 de Octubre 4-2.
Juan Gabriel Abente put 12 de Octubre ahead, but Sergio Diaz levelled in the 28th minute with a clever finish.
The visitors went ahead again just after the hour-mark through Jorge Armoa, and it was Diaz who hit back once more.
Diaz tucked away a finish from close range after a corner went uncleared to make it 2-2 in the 73rd minute.
Wildo Alonso scored an unfortunate own goal with 15 minutes remaining and Cerro Porteno's win was sealed thanks to Jose Ortigoza.
Guarani are three points further adrift after they enjoyed a 3-1 win at Rubio Nu.
Fernando Fernandez, the league's top goalscorer, was on the scoresheet with his 13th strike of the campaign.
Nacional Asuncion won 1-0 at General Diaz and Sol de America overcame Sportivo Luqueno 2-0 in a clash that featured two red cards.
Olimpia were 3-0 winners at Deportivo Capiata.
