SCOTTSDALE, Ariz. -- The Giants’ fifth-starter competition is officially down to two.

Left-hander Kyle Harrison was optioned to Triple-A Sacramento prior to the Giants’ Cactus League finale against the D-backs at Scottsdale Stadium on Saturday afternoon, leaving right-handers Hayden Birdsong and Landen Roupp as the two candidates to round out the club’s Opening Day rotation.

Birdsong and Roupp will have a chance to make their final case on Sunday, when both are expected to pitch for the Giants in their exhibition game against Triple-A Sacramento at Sutter Health Park.

Harrison will start for the River Cats, giving him an opportunity to continue to build up and get stretched out after being slowed at the beginning of camp by an illness that caused him to drop 10 to 15 pounds. Harrison had been viewed as the favorite to join Logan Webb, Justin Verlander, Robbie Ray and Jordan Hicks in San Francisco’s rotation after logging a 4.56 ERA over 24 starts as a rookie last year, but the sickness left him a step behind his competitors and ultimately kept him from making the Opening Day roster for the second straight year.

“When you talk about the competition for the five spot, he was never really in it based on his starting point and where he is right now,” manager Bob Melvin said. “We just need to get him up to speed and get him more innings and get him stretched out longer in games. It was always more kind of between Roupp and Birdsong. I think Kyle was kind of lumped into that kind of unfairly because he was behind in his progression.”

Roupp, who posted a 3.75 ERA over four Cactus League starts and continued to open eyes by striking out 13 over five innings in a High-A game against the Rockies last week, will get the start for the Giants on Sunday. Still, the 23-year-old Birdsong could have the edge for the final rotation spot after recording a 0.75 ERA with 18 strikeouts and no walks over 12 innings in four Cactus League starts.

There’s a chance that both youngsters will end up on the Giants’ pitching staff, as the club could opt to carry one in the rotation and one in the bullpen to start the year. Roupp, 26, earned a spot in the Opening Day bullpen last spring after emerging as one of the biggest surprises in camp, so he could easily slide back into the relief mix this year if needed.

“They’re both going to pitch tomorrow, so we’ll see where it goes,” Melvin said. “But both of them pitched really well.

“It’s been pretty difficult to try to figure out if one of them is in the bullpen, one of them is a starter, and who’s it going to be. I’m not saying that’s the way it’s going to be. That option is there. But it’s been very difficult because both of them pitched really well, and you love seeing that.”

The Giants also optioned right-hander Keaton Winn, who will likely join Harrison in the Triple-A Sacramento rotation to start the year, and reassigned left-hander Joey Lucchesi to Minor League camp.

Lucchesi, 31, came into camp as a non-roster invitee and didn’t allow a run over seven innings in six Cactus League appearances, but the Giants ultimately felt comfortable carrying only one left-hander -- Erik Miller -- in their bullpen.

“To Joey’s case, he pitched well,” Melvin said. “I think he was in seven games and gave up a couple of hits against some lefties when he came in mid-inning. But he’s a starter trying to acclimate to that role. His clean innings were clean, and he pitched well. It’s just about trying to keep as many options as we can. But there’s also some other guys that have performed really well and are going to be on the team. Right now, Joey’s not.”

Ryan Walker, Camilo Doval and Tyler Rogers are also projected to join Miller in the bullpen, leaving Sean Hjelle, Randy Rodríguez, Spencer Bivens, Lou Trivino and Joel Peguero as the other options to fill out the relief corps.