Andre Dawson homered twice in a 12-run fifth inning that enabled the Montreal Expos to beat the Cubs, 17-15, yesterday in Chicago.

Both came with two men on, and, with the two-run homer he hit in the first inning, he tied Chris Speier's club record of eight RBI in a game.

"It was unbelievable, simply unbelievable," Manager Jim Frey of the Cubs said. "The wind wasn't blowing out that hard and people were hitting it in the dark."

Leon Durham of the Cubs thought the score would have been higher except that, "I couldn't see the ball the last two innings."

"It's no big deal," Dawson said. "I've done it before. When your team hits 21 homers in Wrigley Field and only 41 all season at Olympic Stadium (in Montreal), that has to tell you something about Wrigley Field."

He had done it before, against Atlanta in 1979, and is the first major leaguer to hit two homers in an inning twice. He has 21 this season and seven in his last five games.

The big inning gave the Expos a 15-2 lead that they nearly wasted. The Cubs scored 13 runs in the last four innings. After falling behind by 15-3 after six innings, Frey sent in his bench-warmers. In the last three innings, the Cubs had 12 runs on 14 hits and had the tying run at the plate in the ninth. They finished with a season-high 20 hits.

The Expos' 17 hits included five homers.