HOUSTON (AP) -- With 21 games left in this dreadful season, the Chicago Cubs are eyeing a magic number.

No, not the number playoff contending teams are looking at to seal their trip to the postseason. With 86 losses, this club is determined to avoid becoming the first Cubs team to lose 100 games since 1966.

On Monday night they moved a bit closer to that goal with a 4-1 win over the Houston Astros - owners of the only record in baseball worse than theirs.

Dave Sappelt scored the go-ahead run on a wild pitch and had three RBIs to lead the team to the victory.

''Oh yeah, we count down every day - our magic number to not get 100,'' Sappelt said. ''So we definitely have that in the back of our minds.''

Sappelt, who was recalled from Triple-A Iowa on Sept. 1, drove in his first run for the Cubs with a double to the left field corner to put Chicago up 1-0 in the second inning.

The game was tied 1-all in the sixth before Sappelt scored on a wild pitch by Fernando Rodriguez (1-10) that bounced in the dirt and rolled between catcher Jason Castro's legs.

Sappelt came through again in the seventh, knocking a double off the wall in center field just short of the home run line to score a pair of insurance runs.

The Cubs won their fourth straight, matching their season high.

''Those guys are starting to understand how close that 100 losses is,'' Cubs manager Dale Sveum said. ''That's the goal. That's the talk now and obviously they're responding now.''

Justin Maxwell tripled on a ball that rolled up onto Tal's Hill in center field to start Houston's fourth. Castro tied it at 1 with a single to right field on a night when the Astros played with Minute Maid Park's retractable roof open for the first time since May 9.

Chicago starter Chris Volstad (3-10) allowed four hits and a run in five innings for his first win on the road in eight starts this season. Carlos Marmol gave up one hit in a scoreless ninth for his 19th save.

Volstad is 3-3 since being recalled from Iowa on Aug. 1.

''I feel like since I've come back I've been a different pitcher, starting with that L.A. game,'' he said. ''I feel good. I've just got to continue it and keep it going - that whole consistency thing.''

This was an ugly game which included 14 walks, two hit batters, three wild pitches and 24 left on base. By the time the 3 hour, 50 minute game ended, there were only few hundred fans left and most of them were chanting, ''Let's go Cubbies!''

''It seemed like there was a 2-hour rain delay. It was kind of funny how long it took,'' Sveum said.

The Cubs missed several chances to score before finally taking the lead. Welington Castillo got things going in the fourth inning with a single to center field. Volstad singled with two outs before Joe Mather singled to left. Castillo raced toward home on the play, but left fielder J.D. Martinez's throw beat him to the plate to end the inning.

Houston starter Dallas Keuchel was lifted for Chuckie Fick in the fifth inning and he allowed a single by Darwin Barney before plunking Anthony Rizzo. His defense helped him out when the Astros turned a double play on a ball hit by Alfonso Soriano that left Barney at third. Fick intentionally walked Starlin Castro, but escaped the jam by striking out Castillo.

The Astros also missed opportunities in this one. Jimmy Paredes hit a stand-up triple to the corner of right field to start the fifth inning before two walks left the bases loaded with two outs. The Astros came away empty when Matt Dominguez grounded out.

''We had opportunities in the first and the fifth,'' Maxwell said. ''We had (Volstad) on the ropes all night, but we weren't able to push many across.''

Houston interim manager Tony DeFrancesco was disappointed that his team didn't capitalize on its chances.

''I'm glad the guys are getting opportunities to prove they are major league hitters, but at some point, the guys have to be accountable for their at-bats and try to grind them out,'' he said.

Keuchel yielded six hits and a run with two walks in four innings in his first start since returning from Triple-A Oklahoma City.

NOTES: The Astros released RHP Francisco Cordero and purchased the contract of RHP Enerio Del Rosario before Monday's game. ... These teams continue the series on Tuesday when Houston's Jordan Lyles opposes Justin Germano.