Dick Ruthven pitched a two-hitter and Gary Woods and Ryne Sandberg drove in two runs each to key a four-run second inning yesterday in St. Louis, leading the Chicago Cubs to a 4-1 victory over the sagging Cardinals.

The loss dropped the Cardinals into a first-place tie in the National League East with Montreal, which beat New York, 4-3. The surging Cubs are only three games behind.

Ruthven (4-4) allowed Steve Braun's homer, his first since 1980, in the fifth inning. George Hendrick singled in the second for the other St. Louis hit. Ruthven struck out six, walked one and faced just 30 batters.

Keith Moreland and Larry Bowa sandwiched singles around a walk to Jerry Morales to start the Chicago second. After Dave LaPoint (4-4) struck out Jody Davis and Ruthven, Woods singled in two runs. Sandberg's double down the right field line drove in two more and gave Chicago its 13th triumph in 17 games. It was St. Louis' 10th loss in 16 games.

Ruthven retired 14 of the last 15 batters, allowing only a one-out walk to Jamie Quirk in the eighth. He gave the Cubs their second complete game victory in as many days over the Cardinals, who collected just four hits against Steve Trout Saturday night. The Cubs pitching staff had had only one other complete game prior to this series.