GOODYEAR, Ariz. -- After Tuesday, the Reds have exactly one week of exhibition games remaining. However, they still have several questions swirling as they work to whittle down the roster to 25 players ahead of Opening Day on March 28 vs. the Pirates.

Here is what is known:

Number of players in camp: 40, including 21 pitchers.

Players who are out of options: Catcher Curt Casali, left-handed reliever Amir Garrett, outfielder Yasiel Puig and right-handed pitchers Robert Stephenson and Matt Wisler.

Who is sure to open the season on the injured list? Lefty starter Alex Wood hasn’t pitched in a Cactus League game since Feb. 25 because of a sore lower back. Wood just began throwing off of a mound again Monday. Manager David Bell expects him to be ready around mid-April. All indications are that Tyler Mahle will replace Wood in the rotation.

Infielder Alex Blandino has yet to get into a game as he rehabs from reconstructive surgery on his right knee.

Opening Day starter: Right-hander Luis Castillo will start March 28 against the Pirates at Great American Ball Park. He will be followed by Sonny Gray, Tanner Roark and Anthony DeSclafani. The fifth spot is still TBA, but Tyler Mahle appears to have the inside track.

Top remaining roster questions:

Center field

It’s been quite a good battle between Scott Schebler and Nick Senzel, who is MLB Pipeline’s sixth overall prospect. Schebler is batting .429/.606/.762 in 12 games with two homers and 10 walks. Senzel entered Tuesday batting .300/.290/.400 with three doubles as he learns a new position. He’s shown he can handle center field, and his bat is Major League ready. But the club could decide to give him more reps in Triple-A.

Left field:
Matt Kemp came into Tuesday having a stellar spring batting .323/.364/.710 with three homers. Meanwhile, it hasn’t been a great spring for Jesse Winker, who came in batting .147/.194/.353 after he missed most of the 2018 second half because of right shoulder surgery. Kemp has a track record of hot starts (and cold finishes), but Bell has previously noted that he’d like Winker to play regularly. Will one player get the job or is it going to be a left-right platoon situation?

Bullpen:
It appears that the first six spots are locked in for Raisel Iglesias, Jared Hughes, Michael Lorenzen, David Hernandez, Garrett and Zach Duke. If Bell sticks with his plan to have an eight-man bullpen, that leaves two spots.

Sal Romano has often struggled in camp while Cody Reed gave up six runs over one inning on March 2 but nothing else in four games since. Left-handers Wandy Peralta and Ian Krol have had superb camps, and Wisler has also been mostly fantastic.

Bench:
Casali and non-roster utility players Derek Dietrich and Jose Iglesias appear in line for the first three spots. If it’s only a four-man bench, whomever doesn’t play left field between Winker and Kemp would seem likely to claim the final spot. It gets more complicated if Senzel wins the center field job and Schebler winds up on the bench. That would leave players having great camps like catcher/infielder Kyle Farmer and outfielder Phillip Ervin on the outside looking in.