PEORIA, Ariz. -- Suddenly, the Padres' rotation race feels like a two-man battle for one spot.

Logan Allen and Cal Quantrill will get one last chance Sunday to state their cases. Both are slated to pitch in the Padres' Cactus League finale against the Cubs.

Manager Andy Green added a touch of clarity to the rotation picture on Saturday, announcing that veteran left-hander Robbie Erlin will open the season in the bullpen. Last year, Erlin thrived as a jack-of-all-trades on the pitching staff, making occasional spot starts but appearing mostly out of the 'pen.

"He'll start at some point in time, he'll come in and get one lefty at some point in time ... and he'll pitch length out of the 'pen at times," Green said. "He'll do everything before the year's out. That's where his real value's been proven over and over -- his ability to do all of those things."

With Erlin in the bullpen, seven starters remain in camp. Eric Lauer and Joey Lucchesi have already secured their rotation places. Chris Paddack and Matt Strahm aren't quite locks, but they've been excellent this spring and it would be a surprise if they missed out.

As impressive as Nick Margevicius has been this spring, he’s yet to reach Double-A, and he's almost certainly bound for Minor League camp following an outing in a backfield game on Sunday.

That leaves Allen and Quantrill, and it has been an up-and-down spring for both. Allen, the No. 9 prospect in a loaded Padres system, owns a 7.27 ERA this spring. But six of the seven runs he allowed came during one dreadful outing against Kansas City. Otherwise, he has been solid.

Quantrill, meanwhile, owns a 4.63 mark, and his peripheral numbers haven't been very good. The Padres' No. 12 prospect owns a 1.71 WHIP with just seven strikeouts in 11 2/3 innings.

There's still a chance the Padres add another pitcher externally, but that doesn't seem likely. The organization wants to give opportunity to its young arms. Quantrill and Allen will get precisely that on Sunday.

"It's an opportunity to pitch, an opportunity to win, an opportunity to show what they have," Green said. "They're still in camp because we're looking at them as real options for us. ... We'll watch every start and try to learn from it what we can."

Logistical concerns make it unlikely that either Allen or Quantrill breaks camp with the club. Neither is on the team's 40-man roster, meaning the Padres could carry eight relievers on their roster for a few games before eventually promoting their No. 5 starter.

Still, one of them seems bound for San Diego soon enough.

Myers not a regular CF option

The Padres entered camp with a plan to give Wil Myers regular reps in center field. The goal was to find a way to load their lineup with Myers, Franmil Reyes and Hunter Renfroe -- their three best hitters last season, all of whom play corner-outfield spots.

But Myers has struggled in center -- to the point where it's unlikely he plays there with any regularity.

"We need more than what we've got in Spring Training for us to feel like that's our best choice over and over," Green said.

In a crowded outfield mix, Manuel Margot and Franchy Cordero are expected to split time in center. Margot is an excellent defensive option. Cordero, meanwhile, torches right-handed pitching and can play all three outfield spots.

Green left open the possibility that Myers could play center field on occasion -- presumably against a tough lefty.

"At points in time throughout the year, we'll probably consider it," Green said. "We'll probably try it. I don't think he's, at this point in time, solidified himself as our best option in center field."

Perdomo optioned

Right-hander Luis Perdomo was optioned to Minor League camp on Saturday, a day after he surrendered five runs in the ninth inning, including a walk-off three-run homer to the Rockies’ Garrett Hampson.

Perdomo entered camp with a shot at the rotation. After some early struggles, the Padres transitioned him into one-inning relief stints. They felt his fastball velocity might tick up, and his slider might be more effective in short bursts.

Thus far, it hasn't had the desired effect. Perdomo has allowed 11 runs over 7 2/3 frames. He has walked six and struck out eight. Now he will presumably head to Triple-A El Paso, where the Padres hope he embraces his new role.

"We're sending him down with the intent to work out of the bullpen initially, in short bursts, to see if we can get some of that fire out of the arm that we think is in there,” Green said.