The 94-play scrimmage was played before an estimated 15,000 fans at the Los Angeles Coliseum. The offense directed by McDonald won 22-19 over Sanchez's offense.
Turner caught six passes for 85 yards including a 29-yard touchdown pass from Sanchez and an 18-yarder from McDonald.
Sanchez, who will be a redshirt freshman in the fall, completed 13 of 21 passes for 146 yards. He has been playing with the first-string offense since John David Booty sustained a back injury earlier this spring.
McDonald was 19-of-27 for 191 yards and three touchdowns with one interception. His other scoring passes were a 10-yarder to Fred Davis and a 26-yarder to Brad Walker. Brandon Hancock also scored on a 15-yard run, and Ryan Ting returned a punt 75 yards for another TD.
Walker caught seven passes for 75 yards and Hancock gained 21 yards on six carries. Powdrell, playing at fullback, had a 51-yard run.
''It was a good day today,'' USC coach Pete Carroll said. ''We moved the ball around. The quarterbacks got a realistic feel. Sanchez had a very solid day. Turner looked good. Powdrell showed he can run the ball. And I loved the (five) turnovers created by the defense. There were a lot of bright spots. We got in some good, hard work.''
The Trojans finish spring practice Friday and open the season Sept. 2 at Arkansas.