CHICAGO (AP) _ Rookie Scott Downs allowed four hits in seven innings for his first major league win as the Chicago Cubs took advantage of two Florida errors to beat the Marlins 4-2 on Saturday.

Mark Grace hit a sacrifice fly and two runs scored on miscues in a three-run first as the Cubs won for the fourth time in five games.

Downs (1-0), called up from Double-A last Sunday, won in his second career start. He gave up two runs, walked one and struck out six.

Rick Aguilera pitched the ninth for his third save. He struck out Mike Lowell for the final out, giving Aguilera 1,000 career strikeouts.

Ryan Dempster (1-2) gave up four runs _ two earned _ and four hits in 6 2-3 innings. He struck out nine, including the last two batters in the first, part of a stretch in which Dempster retired 19 in a row.

Luis Castillo doubled to lead off the Marlins' first, advanced on a sacrifice and scored on Mark Smith's groundout.

The Cubs capitalized on two Marlins errors to open a 3-1 lead in the first. Eric Young reached on a single that deflected off Dempster's right leg and advanced to third on Ricky Gutierrez's single. Sammy Sosa then singled but the ball struck second base umpire Mark Hirschbeck on the leg, so the ball was ruled dead and Young could not advance.

With the bases loaded, Grace hit a sacrifice fly to score Young. Gutierrez also scored on the play as second baseman Luis Castillo made a throwing error as he tried to throw out Sosa who had taken a large lead at first.

Glenallen Hill then reached on a throwing error by Dempster, allowing Sosa to score and make it 3-1.

Kevin Millar led off the fifth with his second home run to cut the lead to 3-2.

The Cubs added a run with two out in the seventh on pinch-hitter Jose Nieves' RBI single.

Notes: Fog rolled in from Lake Michigan during the seventh inning. ... Gutierrez extended his hitting streak to a career-high 10 games with a single in the first. ... Hirschbeck missed a half-inning for treatment on his leg. ... The Marlins started Saturday tied for first in the NL East. It is the first time in franchise history the Marlins have been in first this late in the season. In 1997 when the Marlins won the World Series, they finished in second place.