The win, coming by a final of 66-54, was the first for Marks and the Mustangs since the season-opener against Kuyper College on Nov. 10.
Marks' 27-point, 18-rebound effort marked her fourth double-double of the 2012-13 campaign. The senior forward is averaging 17.5 points per game and 9.1 rebounds per game through 14 games this season.
In a game that featured five first half ties and a three-point halftime differential, the Mustangs or Saints never held a double-digit lead until the Mustangs iced the contest with free throws at the end.
Ciara Moore (Detroit, Mich./Northwestern) helped lead the Mustangs to their second victory of 2012-13 behind 16 points, six steals and four assists.
The win over St. Clair ends a 12-game skid for the Mustangs.
In the first game at the Davenport Holiday Tournament, the Mustangs dropped a 64-50 decision to fellow NAIA school, Holy Cross College (Ind.).