PHOENIX -- The D-backs made their final roster move early Thursday morning, designating third baseman Emmanuel Rivera for assignment just before unveiling their Opening Day roster.

That means rookie infielder Blaze Alexander will be making his big league debut when he slots in at designated hitter for Thursday night’s season opener against the Rockies at Chase Field.

Here’s a quick look at how the roster shook out:

Catcher (2): Gabriel Moreno, Tucker Barnhart
Moreno’s first full season in the big leagues was a smashing success, and he is the unquestioned starter behind the plate. As for who will back him up, that’s less of a sure thing. Jose Herrera saw time in that role last year, and the D-backs signed the veteran Barnhart to a Minor League deal to provide depth for that spot.

First baseman (1): Christian Walker
Walker is once again expected to be a key part of the Arizona lineup, and he doesn’t come out of the lineup often, as evidenced by his 160 games played in 2022 and 157 in 2023. They will try and get him more rest this year, though.

Second baseman (1): Ketel Marte
It was a big year for Marte in 2023, and while others in the lineup get a lot of attention, it’s Marte that really makes things go. When he’s hitting, the D-backs are usually playing winning baseball. He has been swinging a very hot bat this spring while looking good on defense.

Shortstop (1): Geraldo Perdomo
D-backs manager Torey Lovullo said Perdomo will be the everyday shortstop, which makes sense given what the switch-hitter did for the team last season when he made the National League All-Star team.

Third baseman (1): Eugenio Suárez
The D-backs acquired Suárez in a deal with the Mariners during the offseason, and they are hoping he will be able to handle the bulk of the load at third base, which has been a bit of a revolving door for Arizona in recent years.

Outfielders (3): Lourdes Gurriel Jr., Alek Thomas, Corbin Carroll
Gurriel was re-signed as the third member of this outfield. Carroll won the NL Rookie of the Year Award while Thomas played his usual outstanding defense -- he was a Gold Glove finalist -- and showed some strides at the plate.

DH (1): Joc Pederson
Randal Grichuk looked like the right-handed half of a platoon at this spot, but he is still recovering from ankle surgery.

Bench/Utility (3): Jake McCarthy, Jace Peterson, Blaze Alexander
No. 15 prospect Blaze Alexander will back up at shortstop. Peterson is owed $3 million and looked good at the plate this spring.

Starting pitchers (5): RHP Zac Gallen, RHP Merrill Kelly, RHP Brandon Pfaadt, LHP Tommy Henry, RHP Ryne Nelson
The D-backs return their top two pitchers from last season along with Pfaadt. With Eduardo Rodriguez starting the season on the injured list, lefty Henry filled the final spot.

Relief pitchers (8): RHP Kevin Ginkel, RHP Ryan Thompson, LHP Kyle Nelson, RHP Miguel Castro, RHP Scott McGough, RHP Luis Frias, LHP Joe Mantiply, RHP Bryce Jarvis
The bullpen is always the hardest part to project, and it’s also the one that is most likely to change one week into the season depending on usage. The one thing this group lacks is length, which is something the D-backs will likely want early. Henry or Nelson could serve in that role.