When the D-backs re-open the season March 31 against the Giants, though, it still appears as though only one of them will make the team with Cliff Pennington serving as the backup.
This is not the first time these two have competed against each other, though.
The previous time they were on different teams, but things were just as nip-and-tuck then.
Back in the fall of 2012, Gregorius was playing for the Peoria Javelinas while Owings starred for the Salt River Rafters in the Arizona Fall League.
Those were the two best teams in the AFL that year and the pair of young shortstops were on opposite sides in a championship game like no other the league had ever seen -- one decided in part on a protested call.
"It was a really, really good game," Owings said. "Everyone was amped up and into it. It was a cool atmosphere, it was on MLB Network."
The contested play came in the bottom of the seventh inning when Owings lifted a fly ball to right where it was caught. Brian Goodwin tagged up from third and scored what would have been the tying run.
However, catcher Mike Zunino stepped on home plate in an attempt to appeal the play and the home-plate umpire ruled that Goodwin was safe.
Then the Javelinas appealed at third base that Goodwin had left early, and it was ruled that he had, so Goodwin was out and the Rafters still trailed, 4-3.
Rafters manager Matt Williams, who at the time was the D-backs' third-base coach, protested the call based on the fact that the defensive team should not be able to appeal the same play at multiple bases.
After the game, the protest was denied when it was learned that a team is allowed to appeal a play at multiple bases.
"It was actually kind of fun," Gregorius said. "Well, I'm not going to lie -- at the time that play happened no one knew the rule, at least I didn't. Then when they told us about the rule, we were right, so that was good."
To this day, Owings maintains the umpires made the incorrect call.
"I went and looked a replay later and he didn't leave [third] early so I don't know what happened there," Owings said.
Gregorius, then in the Reds' system, hit .284 that fall and caught the eye of Arizona general manager Kevin Towers, who wound up completing a three-team trade for him a month after the Fall League ended.
"I enjoyed playing in the Fall League and being around the guys," Gregorius said. "Everybody was comfortable with each other. It was amazing being there with the guys. It was great to face all the good pitching because it makes you get better, too."
The Peoria team that Gregorius played on was a tight-knit bunch, especially considering how the team was comprised of players from different organizations.
"We talked about everything," Gregorius said. "We didn't really know each other. I mean, we had played against each other during the season, but we didn't talk much. Then we got together in the Fall League for like two days and it was like we had always been together. We talked a lot and everyone was helping each other out."
Owings, now the second-ranked prospect in the D-backs' system, hit .275 and showcased his skills for Williams, who in turn passed along positive reports to manager Kirk Gibson.
In 2013, Owings would go on to win the Pacific Coast League Most Valuable Player Award and his strong performance at Triple-A Reno earned him a September callup, which in turn set him up to battle for the starting big league job this spring.
"It was great to face even better competition than in the regular season," Owings said of the Fall League. "And I got a lot of playing time, so I think that did help me out a lot for the next year."