Wally Backman's two-out single in the seventh inning, his third hit of the game, scored Roger McDowell from second to give the New York Mets a 6-4 victory yesterday over the Cubs, their fifth in five games against Chicago at Shea Stadium this year.

Backman, who has an eight-game hitting streak, also scored twice.

"Wally's been a favorite of mine for the last three years," said Mets Manager Davey Johnson. "I picked him over the incumbent (Bob Bailor) when I came here. I'm not surprised about his hitting. He batted .316 for me at Tidewater two years ago."

New York has won five in a row. Chicago has lost five in a row. The pitching-thin Cubs also lost starter Dick Ruthven with a bruised right big toe after he was hit by Keith Hernandez's first-inning line drive.

With two out in the seventh, McDowell singled to center off reliever Warren Brusstar (2-2), the third of four Cubs pitchers. Len Dykstra singled and Backman followed with the game-winner. Howard Johnson singled home a run in the eighth.

McDowell (6-4) pitched the last three innings in relief of starter Ron Darling, allowing one hit.

Keith Moreland broke a 3-3 tie in the sixth with his ninth home run of the season, the Cubs' third one-run homer of the game off Darling. Jody Davis had the other two. The Mets tied at 4 in the sixth when Backman doubled off Ron Meridith and scored on Hernandez's single to right.