Larry Parrish singled home Warren Cromartie from third in the 11th inning to give host Montreal a split in its doubleheader with St. Louis.

The Cardinals won the opener as Ken Oberkfell drove in three runs with a bases-loaded triple. The split allowed the second-place Expos to remain 2 1/2 games behind the Cardinals in the National League East.

Cromartie led off the 11th with a single against reliever Jim Kaat (6-5), advanced to second on a sacrifice by Gary Carter and went to third on Rowland Office's single. Parrish brought him in with a single to center.

Trailing, 4-2, the Expos tied the score with two runs in the eighth inning. Rookie Terry Franconia homered and Andre Dawson followed with a single. He moved to second on the same play when shortstop Garry Templeton threw the ball away, advanced to third on an infield out and scored the tying run on Gary Carter's single.

In the first inning, St. Louis took a 3-0 lead when Dane Iorg singled home Keith Hernandez and Oberkfell followed with a two-run double. Montreal got its first run in the seventh inning on a run-scoring single by Mike Phillips.

In the opener, the Cardinals broke the game open in the eighth with a four-run rally against rookie Tom Gorman. Gorman loaded the bases by yielding consecutive singles to Tom Herr, Templeton and Hernandez and pinch hitter Steve Braun was walked by reliever Stan Bahnsen to force in a run. Oberkfell followed with his triple against the right center field wall to help make a winner of Bob Forsch (9-5), who worked the first seven innings.