Austin Slater's first assignment after returning from the injured list will come against a familiar face.

The Giants activated Slater on Saturday and slotted him back into the leadoff spot against D-backs left-hander Madison Bumgarner, who was set to make his first start at Oracle Park as an opposing pitcher. To clear a spot on the 28-man roster, the Giants optioned outfielder Steven Duggar to the alternate training site in Sacramento.

Slater, 27, had emerged as a breakout hitter for the Giants before landing on the IL last month, batting .347 with a 1.111 OPS, four home runs and six stolen bases over 19 games this season.

“Slater has just swung the bat so well against lefties and righties, but in particular, he’s been excellent against left-handed pitching,” manager Gabe Kapler said. “Obviously, Madison is tough on all hitters, but in particular on lefties, so it's nice to be able to get a heavy right-handed-hitting lineup out there with Slater at the top.”

Slater missed 11 games with a left groin strain, but he’s still dealing with a flexor strain in his right elbow that has prevented him from playing the outfield since Aug. 11. He started at designated hitter on Saturday, though Kapler said Slater has resumed throwing to the bases and is close to receiving the final medical clearance needed to return to the outfield.

“We would prefer that he play the outfield when he plays,” Kapler said. “At the same time, it's worth working to get his bat in the lineup, even when his arm isn’t 100 percent. We have to make sure that when he does go out there and play the outfield, he can really rip on it, and we can feel safe and he can feel comfortable. We'll keep looking at that day to day. It's improving and getting better every single day, but we’re going to wait for that final green light where we know he's going to be safe.”

The Giants stacked their lineup with right-handed hitters against Bumgarner, who returned from the IL after missing time with a back strain. Mike Yastrzemski and Brandon Belt were the lone lefty bats to start against the former Giants ace, as newcomer Daniel Robertson earned the starting nod at shortstop over Brandon Crawford.

Belt has made it extremely difficult for Kapler to take him out of the lineup, as he entered Saturday slashing .500/.574/.981 (26-for-52) with five home runs and 13 RBIs over his last 17 games.

“Belt has a tremendous level of confidence right now in the batter's box,” Kapler said. “I certainly have that same level of confidence in him. Over the last couple of weeks, he's been among the top couple of hitters in all of baseball. He’s coming off a great game, and I just believe in him and want to reward him for that performance and show the confidence level in him.”

Injury updates

Drew Smyly (left index finger sprain) and Jeff Samardzija (right shoulder inflammation) each threw approximately 50 pitches over three innings in a simulated game at Oracle Park on Saturday. Kapler said the veteran starters mixed in all their pitches and came out looking healthy, though the Giants are still in the process of determining when they’ll be available to rejoin the club.

“Everything's on the table at this point,” Kapler said. “I think it's going to be based on the needs of our club, obviously, and timing. Neither Samardzija nor Smyly is going to be ready in the next couple of days, obviously, after throwing 50 pitches. We've got a couple of days to deliberate and think through things. We'll make decisions after having additional discussions.”

Standing up to cancer

For the fifth consecutive year on Saturday, the Giants were among those clubs to wear gold ribbon decals and wristbands on the field to raise awareness for childhood cancer. The gesture was in recognition of Major League Baseball’s “Childhood Cancer Awareness Day,” held during Childhood Cancer Awareness Month in collaboration with Stand Up To Cancer (SU2C).