The 21-year-old Torres, who came off the bench in the USA's last two World Cup qualifiers, scored for Pachuca in the 21st minute with a 25-yard shot to extend its lead to 2-0 over Jaguares. He was subbed in the 75th minute with the score tied 2-1. Pachuca got another goal thanks to a Gilberto Mora own goal.
Torres played in 16 of Pachuca's 17 regular-season Clausura 2009 games but the playoff strike was his first of the year. He last scored in August in the Apertura 2008.
The 23-year-old Vidal didn't see action for Indios until the 12th game of the Clausura 2009 but started the last seven games, including his 90-minute performance in the first-leg quarterfinal upset of defending champ Toluca.
Nunez, 23, assisted on Puebla's second goal in a 3-1 win at Monterrey. Nunez, who played youth ball for the Dallas Texans, plays for Honduras' national team. He joined Puebla this year after playing in MLS for FC Dallas (2004-07) and Chivas USA (2007-08), and for Honduras club Olimpia.
In the other quarterfinal, host Tecos downed Pumas, 2-0.
Clausura 2009, Quarterfinals, second leg
Saturday UNAM Pumas-UAG Tecos (TV: Telemundo, 6 pm ET)
Saturday Monterrey-Puebla (TV: Telemundo, 8 pm ET)
Sunday TOLUCA-INDIOS (TV: Telemundo, 1 pm ET)
Sunday PACHUCA-CHIAPAS (TV: Telefutura, 7 pm ET)