PEORIA, Ariz. -- Padres right-hander Joe Musgrove fractured his left big toe on Monday, the team announced early Tuesday morning, putting his status for Opening Day in serious doubt.

Musgrove sustained the injury in the team's weight room when he dropped a kettlebell on his foot while working out.

Manager Bob Melvin offered no specific timetable for Musgrove's return, other than to note that it would be "a minimum of a couple weeks before he starts throwing again."

"It's kind of tough to forecast," Melvin added. "When you have a broken toe, it's going to be more about how it heals and, certainly, if it's a pain tolerance thing, Joe would be one of those guys, it would be sooner than later."

What it means

If Musgrove were to miss the start of the season, it'd be a significant blow to the Padres' rotation. The 30-year-old right-hander was part of a trio -- alongside Yu Darvish and Blake Snell -- that made up a particularly formidable front of the rotation.

After signing a five-year extension with his hometown club last summer, Musgrove was a candidate to make his first Opening Day start. He's coming off his first All-Star Game in a season in which he posted a 2.93 ERA and a similarly excellent postseason.

Of course, it's better Musgrove sustained the injury in late February than midseason, with perhaps the bulk of his recovery time coming before the regular season begins.

How do the Padres adjust their rotation?

When Michael Wacha signed, the team essentially confirmed its plan to use a six-man rotation at the start of the season. Behind their big three, the Padres planned to line up Wacha, Seth Lugo and Nick Martinez, in some order.

Those six-man-rotation plans are now back in question. If Musgrove opens the season on the injured list, it's possible the Padres would still open with six starting pitchers. They had plenty of success employing such a strategy last season, and they begin the year with 24 games in 25 days.

But if that's the Padres¡¯ preference, they'd first need one of their depth starters to step up and win that final rotation spot in camp.

"We'll probably make that decision the farther we go into camp, if we have guys stretched out that we think can handle that," Melvin said. "And/or is it more prudent to go with another length arm in the bullpen and five [starters]?

"We are up against [it], as far as scheduling goes -- 24 out of the first 25 -- so we'll see how we get there."

Who are the candidates to replace Musgrove?

The Padres have quite a few. But at this point, they¡¯re only candidates for a job that might not actually become available. As Melvin noted, it's possible the team would open with an eight-man bullpen and a five-man rotation instead. (This spring roster is overflowing with relief options.)

Here are the early candidates for a potential No. 6 starter role: Jay Groome, Brent Honeywell, Ryan Weathers, Reiss Knehr, Julio Teheran and Adrian Morejon.

It's still unclear whether the Padres plan to stretch Morejon toward a full starter's workload. (He's been solid in the 'pen and has never pitched more than 66 innings in a season professionally.) Morejon has yet to appear in a Cactus League game, but the rest of that group has looked mostly sharp early in camp.

"Everybody's semi-impressed on the pitching end," Melvin said. "It's once you get deeper into games, once you get some of these guys into games against big league lineups, that's when you get a better indication. But at first look, all these guys have pitched pretty well."

Before Monday, that group was merely vying for a length role in the bullpen. Suddenly, there might be a bit more on the table.