Gary Matthews homered with no one on base and Mike Schmidt a two-run homer in a three-run third inning that helped the Phillies to an 8-2 victory over the Chicago Cubs last night in Philadelphia.

Phillies right-hander John Denny, acquired from Cleveland last Sept. 11, allowed eight hits, struck out three and walked one in his first victory since July 9; he was 0-2 in four starts for the Phillies in the last three weeks of the '82 season.

"It can have a psychological effect if you allow it to," said Denny, who pitched the Phillies' first complete game of the season. "It's just like anything else. But the pressure is what you make of it. I felt good all during spring training and I knew it would be a matter of time before I put a good game together. Now I hope I can continue."

The Phillies trailed, 2-0, with two out and nobody on in the third when Paul Moskau (0-1) ran into trouble. Matthews, who had a single and a double later in the game, hit his third homer of the season, Joe Morgan walked and Schmidt drove in two more with his fourth homer.

The Phillies had three runs in the fourth, chasing Moskau.