The Trojans also fell to 34-7 in all-time home openers, with a 7-3 mark at the Galen Center.
Marquette pulled even in the all-time series with the Trojans at 1-1 and handed USC its first loss to an unranked opponent since Nov. 21, 2014 (at Oregon State).
The Golden Eagles became just the fourth non-conference opponent to claim a victory over the Trojans at the Galen Center. The other three teams to hold that distinction are Hawai'i (2008, 2009), Texas A&M (2014), and Florida (2014).
Junior OPP Niki Withers set a new USC career high with 13 kills. She had 15 kills in 2015.
Freshman OH Alyse Ford recorded a new career mark with eight digs.
Junior S Reni Meyer-Whalley logged the Trojans' first double-double of the season with 25 assists and 11 digs.