MESA, Ariz. -- Locking down the final two spots of the Reds' rotation has gotten more complicated in recent days.

Manager David Bell conceded on Saturday that Luke Weaver's chances of being ready for the start of the season are in doubt. Weaver left a Minor League game on Monday with soreness in his right forearm.

"The next couple of days will tell us a lot more. I think it’s going to be really close, though," Bell said. "I think we’d have to push pretty hard to get him ready for Opening Day."

Weaver, who was signed to a one-year, $2 million contract on Jan. 13, resumed throwing on Friday but isn't scheduled to get back on a mound for a few days.

"Everything went well enough yesterday where now he’ll play catch from a longer distance as a next step," Bell said.

Another candidate, Luis Cessa, has been away from the team to pitch for Mexico in the World Baseball Classic. However, Cessa has only pitched once during that span -- a two-inning relief appearance against Colombia on March 11.

"It’s still possible he would be able to be in our rotation and get up to 4-5 innings," Bell said. "... If, for some reason, that doesn’t happen, he has a spot on our staff. He can help us as a reliever, but he’s still in the mix for the rotation."

The other rotation candidates are Connor Overton, Chase Anderson and Brandon Williamson.

Cincinnati's No. 10-ranked prospect by MLB Pipeline, Williamson pitched four innings in Saturday's 7-1 win over the A's and allowed one earned run and two hits with two walks and two strikeouts.

Walks have been a mild issue for Williamson during camp. He has six of them along with 12 hits and 11 strikeouts over 11 innings. But he felt more in command on Saturday.

"It frustrates me, because I didn’t feel like I was that wild to walk two guys," Williamson said. "It was just one batter, and I got right back in it. I never felt out of control. I had a couple heaters that missed. I felt like I could have gone pretty deep today in the game. I’d say that’s pretty consistent."

Williamson has a 6.55 ERA through five games (three starts). Against Oakland, he had intriguing moments, like getting Tony Kemp to hit an off-speed pitch for an inning-ending grounder to first base in the second. In the fourth, Williamson struck out Ramón Laureano with a 69-mph big curveball while slide-stepping.

"I’d like to think I’ve done everything I can to have the opportunity to make the club right away, and I certainly want to," Williamson said. "I’ve been putting a lot of attention in everything I can do to make the club, I just don’t know where I’m at relative to the other couple guys."

Overton has a 14.85 ERA through three games (two starts), and is often giving up hard contact. But his most recent outing -- a 3 1/3-inning start vs. the Cubs -- was wiped out when the game was called by rain before the fifth inning. Overton, who will pitch in a Minor League game on Monday, looked much sharper vs. Chicago and gained a lot of confidence.

Anderson, who was signed to a Minor League contract last month after camp opened, was not added to the big league camp roster until March 7. He pitched two scoreless innings in his first start but gave up three earned runs and six hits over three innings in his second. Anderson pitched in a Minor League game on Friday.

Anderson pitched in nine games (seven starts) for the Reds towards the end of the 2022 season.

"We like a lot about Chase and what he brings to our team," Bell said. "I'm glad he's in our camp. I'm glad he came back, signed with us. We loved having him here. [The] next 10 days will tell us a lot."

There are two off-days in the schedule in the first nine days of the regular season, but going with a four-man rotation isn't necessarily a solution -- especially if it requires sending someone to the Minors. Players optioned cannot be recalled for at least 15 days. Following those two off-days, the Reds play 19 straight games and would certainly need a fifth starter for that stretch.