The San Francisco Giants are on the fringe of a spot in the expanded Major League Baseball postseason field during the first week of September, and they have a chance to strengthen their position with a four-game home series against the free-falling Arizona Diamondbacks that begin Friday.

The Giants (18-20) have won three of their last four games and took two of three from the Diamondbacks last weekend at Phoenix. They didn't see former teammate Madison Bumgarner, who has been on the injured list.

Bumgarner is scheduled to make his return this weekend, but first there is a Friday night game to play.

"The ball's in our court," Giants manager Gabe Kapler told reporters after Wednesday's 9-6 loss at Colorado. "We have the ability to control our destiny. We're swinging the bats really well. We've got a lineup that can put up runs, Coors Field or not. And we can do that against righties and lefties. And what we're starting to see is our starters are giving us a chance to win games. Outside of (Wednesday), our bullpen has been pretty good as well.

"We need it all to come together in these last couple of weeks. I think our schedule is a manageable one," Kapler added.

That schedule includes eight remaining games against teams that traded a lot of pieces at the deadline, the Diamondbacks and Seattle Mariners.

The Giants have left-hander Tyler Anderson (1-2, 4.75 ERA) on the mound Friday. Anderson will start his third consecutive game against Arizona with vastly differing results in the previous two.

On Aug. 22, he pitched a complete-game three-hitter, allowing an unearned run in a 5-1 win over the Diamondbacks in San Francisco. On Aug. 28, he got roughed up for seven runs on nine hits in 4 2/3 innings at Chase Field.

The Diamondbacks (14-24) have lost five in a row, swept in a three-game series by the division-leading Los Angeles Dodgers in a series that ended Thursday night. Arizona has dropped 13 of its last 14 games.

The Diamondbacks (14-24) have lost eight straight road games and are 1-5 this season against San Francisco, losing all three games in their first series at Oracle Park from Aug. 21-23.

"Things just aren't going the way we want," outfielder David Peralta told reporters. "We prepare ourselves every day the best way we can. Pretty good contact, we couldn't find a hole and that's how baseball works sometimes. Sometimes it works your way, sometimes it doesn't work."

The Diamondbacks are running out of games to get things turned around, and have turned to some younger players to step into bigger roles after four veterans were traded earlier in the week.

"We have to come with the mentality to win every day. It doesn't matter who we have right now or in last place or not," Peralta said. "We can never give up. You have to keep working hard and keep a positive mentality."

Taylor Clarke is set to make his third start of the season for Arizona Friday, after opening the season in the bullpen. Clarke (1-0, 2.22) is 1-2 with a 6.75 ERA in four career starts against the Giants, his highest number of starts against any opponent.