SCOTTSDALE, Ariz. -- At the last minute on Saturday, Robbie Erlin was handed the perfect opportunity to make his case for the rotation. The level-headed lefty made the most of it.
The circumstances weren't ideal, with right-hander Bryan Mitchell a late scratch on Saturday due to neck stiffness. Erlin, who was initially slated to throw in a back-field game, took the mound against Arizona instead. Afterward, Green downplayed the severity of Mitchell's injury, saying he expects the right-hander to pitch in the next couple days.
In Mitchell's place, Erlin was sharp over 3 2/3 innings of one-run ball, in which he struck out four D-backs. He allowed only two hits, both singles to second baseman Chris Owings.
"I woke up today ready to pitch," Erlin said. "It was just a matter of where it was going to be. I was already loose and getting ready to go, and I just headed over to this side of town."
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Before the game -- which finished in a 3-3 tie -- manager Andy Green lamented the fact that his congested rotation race had limited innings to go around. Saturday would've marked Erlin's second consecutive back-field start against mostly Minor Leaguers. Instead, he faced a D-backs lineup filled with regulars.
"You've always got to be ready to take advantage of your circumstances, and Robbie was ready today," Green said. "It gave us a look at where he's at -- and against some really good hitters."
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Erlin missed the 2017 season due to Tommy John surgery, but he returned to full health last fall. He hasn't felt any effects from the injury this spring.
He's among four starters vying for the final two places in the Padres' rotation, along with Luis Perdomo, Tyson Ross and Christopher Young. Should Erlin miss out, he's also a candidate for a spot in the bullpen.
"It was a constructive outing," Erlin said. "I dialed in some stuff I'd been working on. It felt good. It felt like [the] pitch execution was better than it was my last outing. It was a good building block moving forward and getting ready for the regular season."
Room for three catchers?
It's possible -- though maybe not probable -- that the Padres carry three catchers on their Opening Day roster, clearing room for both A.J. Ellis and Raffy Lopez to make the club as backups to Austin Hedges.
Lopez doubled on Saturday, and is now 6-for-17 (.353) with four extra-base hits and four walks this spring. The Padres could choose to keep him as a lefty bat off the bench and as a platoon threat against tricky right-handers.
"There's real value in what they both bring to the table," said Green. "It's obvious what A.J. Ellis brings to the table, and it's obvious what Raffy Lopez brings to the table. They're very distinct things."

It's unlikely Ellis gets left off the Opening Day squad, putting Lopez at the mercy of some roster math. For the 25th spot on the roster, the Padres will likely choose from Lopez, an extra infielder or an extra reliever.
Right-field videoboard installed
The Padres' completed the installation of their right-field videoboard on Friday, the latest upgrade to Petco Park ahead of the 2018 season.
The HD videoboard, which checks in at 1,722 square feet, looms above the middle section of the second deck in right field, below the stadium's light fixture.

Camp battles
• Carlos Asuaje smashed a two-run triple in the eighth on Saturday, tying the game at 3. He and Cory Spangenberg are locked into an extremely tight battle for the starting second-base job.
"That's the toughest [evaluation] in camp right now," Green said. "They're matching each other at-bat for at-bat. That's the kind of competition you like to see. There's no clear-cut favorite."
• Hunter Renfroe crushed his fourth homer of the spring on Saturday, a solo shot against D-backs right-hander Ryan Atkinson. He's moving closer to securing one of two remaining outfield places.
Injury updates
• Outfielder Franchy Cordero is nearing a return from the groin injury that has kept him out of action for the past two days. The Padres are hopeful he'll be available Tuesday, following Monday's off-day.
• Right-hander Colin Rea has not yet resumed throwing, as he deals with a right lat strain that he sustained earlier this spring. Rea, who missed all of last season with Tommy John surgery, is a candidate to be placed on the 60-day disabled list, unless his recovery begins to move quicker.
Up next
Right-hander Tyson Ross has a major chance to make a rotation statement Sunday when the Padres head to Camelback Ranch to face the Dodgers at 1:05 p.m. PT. A big performance against a division rival would go a long way toward increasing his roster chances. Watch the game live on MLB.TV.