Palos Verdes Chadwick struggled with St. Margaret's but managed to hold off the Tartans, 13-0, in a Southern Section Division XII playoff game Friday night at Redondo Union High School.
St. Margaret's ended its season at 5-5; Chadwick is 9-1.
St. Margaret's moved the ball to Chadwick's 29-yard line on its opening possession before quarterback Dylan Gilbert threw the first of his four interceptions.
Chadwick could not take advantage of the turnover, punting on the ensuing drive.
The Dolphins scored their first touchdown with 8 minutes 19 seconds left in the first half, when Paul de Costa caught a 38-yard pass from Ian Hoge for a 7-0 lead.
Chadwick's defense held St. Margaret's to 56 yards in total offense in the first half. Gilbert, who had thrown for more than 1,000 yards during the regular season, was held to only 14 in the first half.
With 4:19 left in the third quarter, Kunle Williams scored on an 18-yard run to close the scoring.
St. Margaret's had 109 yards in total offense and was outgained by Chadwick's penalty yardage. The Dolphins were flagged 16 times 166 yards.