Davey Lopes, who earlier made two sensational catches in left field, hit a tie-breaking two-run homer in the eighth inning in Chicago yesterday as the Cubs beat the Houston Astros, 5-4.

With one out in the eighth, Ryne Sandberg singled off Houston reliever Mark Ross, stole second and scored ahead of Lopes' third homer of the season for a 5-3 Chicago lead. It was the seventh home run of the game.

Lee Smith (2-0) was the winner, working the last two innings. He yielded a run in the ninth on a walk, Enos Cabell's single and Bill Doran's sacrifice fly. Doran went to third on Terry Puhl's double but Lopes made a running catch of Denny Walling's fly ball to end the game.

Lopes called it "a game you put in your memories."

Lopes has been used extensively by the Cubs and has played all three outfield positions this season in addition to third base. Most of his career was as a second baseman with the Los Angeles Dodgers.

Bearing a huge scratch on his left arm from slamming into the vines on Wrigley Field's outfield wall, Lopes took an extra-base hit away from Walling in the third inning and also robbed Kevin Bass in the fifth. Both times he crashed into the vines. "I thought the vines would be a cushion," said Lopes, "but I was wrong."

It was a battle of home run or nothing through the first seven innings with each team hitting three one-run homers before a capacity Wrigley Field crowd of 36,278.

Puhl, Bass and Jerry Mumphrey homered for the Astros and Leon Durham, Steve Lake and Ron Cey did for the Cubs.

Starters Scott Sanderson for Chicago and Joe Niekro for Houston each went seven innings.