The Silver Stars, who lost to an Eastern Conference team for the first time all season after 14 wins, were led by Sophia Young's 21 points and 16 from Ann Wauters.
Detroit didn't get its first lead until 2:19 into the second quarter when Smith made two free throws to go up 21–20 before the Shock outscored San Antonio 21-12 the rest of the half for the double-digit margin.
Darling strained her right calf and Lawson-Wade sprained her right ankle during Saturday's Game 2 victory over Los Angeles in the Western Conference semifinals.
Katie Smith scored 22 points and the Shock built a big lead in the first quarter, then hung on to beat the San Antonio Silver Stars 69–61 and go up 2–0.
Plenette Pierson, wearing a protective wrap on her shoulder after missing Game 1 with an injury, answered with a reverse layup for her only points of the night.
Detroit swept the league's best regular-season team, winning the clincher at the Eastern Michigan University Convocation Center, a venue forced upon them because of a scheduling conflict.
The Shock had been one of the league's best teams for much of the year, but sputtered a bit after losing top post player Cheryl Ford to a season-ending knee injury in July.