A brace from Argentine striker Martin Bravo led Pumas to victory in Mexico City with the home side piling on five goals to claim their first win in five games in all competitions.
With Cruz Azul (28 points) and Toluca (25) leading the charge in Mexico's top flight, Pumas' win ensured they remain in the hunt for the title - albeit 10 points behind the leaders - in third position.
Pumas had not won a home league fixture since February 2 before Sunday's game but it did not take them long to get on top against Atlante with Bravo nodding a corner into the net from close range in the 22nd minute.
The 27-year-old Argentine played a key role in Pumas' second goal 17 minutes later, as his shot was parried into the path of Ismael Sosa, who scored.
Bravo completed his brace a minute before half-time, finding a pocket of space at the top of the box and turning sharply, before firing his shot past Atlante goalkeeper Eder Patino.
Diego Lagos made it 4-0 for the hosts on the hour mark with a first-time shot, while Dario Veron thrashed home Pumas' fifth goal in the 88th minute, after controlling a corner with his thigh.
On Saturday, Cruz Azul trailed 1-0 at half-time thanks to Richard Ruiz's goal for Tijuana just before the break but the leaders fought back in the second half to register their ninth win of the season.
Marco Fabian scored in the 47th and 69th minutes as Cruz Azul bounced back from consecutive defeats to Tigres UANL and Sporting Kansas City in the CONCACAF Champions League.
Toluca remain a victory behind Cruz Azul after their 2-0 win at Queretaro on Friday, while Pachuca are fourth with 17 points, following a 3-1 loss to fifth-placed Santos Laguna (16 points).
In other results, Tigres extended their unbeaten streak to 11 games in all competitions with a 1-0 win over Puebla, Atlas trumped Veracruz 1-0, Chiapas drew 2-2 with America, Morelia won 1-0 at Monterrey and Guadalajara defeated Leon 1-0.
