KISSIMMEE, Florida (AP) Jon Singleton says he knows why he's struggled in parts of two seasons in the majors.

The top candidate to take over at first base for the Houston Astros was simply trying to do too much.

''You can't go out and try to beat the whole world in one day,'' he said. ''So I'm just trying to take it slow.''

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Singleton has been one of the most powerful hitters in Triple-A over the last two years, but that success hasn't yet translated to the majors. In 95 games in 2014 he hit 13 homers and 44 RBIs, but hit just .168. He was with the Astros for only 19 games last year and finished with one homer, six RBIs and a .191 average and was not included on the team's postseason roster.

Then the Astros didn't offer a contract to slugger Chris Carter this offseason and Singleton had another chance to become the everyday first baseman. Though Houston is counting on Singleton to step up, manager A.J. Hinch won't say this is a make-or-break situation for the 24-year-old.

''I think it's hard to say that about somebody in his early 20s,'' Hinch said. ''I don't think it's career-defining as much as I think this is the best opportunity he's had to be a contributor on a good team as a potential starting first baseman.''

Matt Duffy, Houston's fourth-ranked prospect A.J. Reed and Tyler White are also vying for the position. But the Astros would prefer to see Singleton lock up the position after he signed a five-year, $10 million contract in 2014 that includes three club options.

''Jon Singleton enters with the most experience and certainly the most eyes on him,'' Hinch said. ''Other guys are going to factor in as the spring goes on depending on how it goes ... but (Singleton's) got the first look and he's spent the most time on the shuttle between Triple-A and the big leagues to where he's going to get the initial look.''

Singleton had 22 homers, 25 doubles and 83 RBIs in 102 games last season for Triple-A Fresno. His inability to replicate that success in the majors weighed on the left-handed hitter.

''It got to me,'' he said. ''It definitely bothered me because I knew what I was capable of and I wanted to be that person so bad. And I was just so aggressive and just kept pushing and kept pushing and kept pushing. Now I'm trying to just sit back and play the game.''

He hopes that his more laid-back approach at the plate will lead to improvement this spring and allow him to grab the starting job. He's getting some help this spring from Jeff Bagwell, the best first baseman in franchise history.

Bagwell narrowly missed being voted into the Hall of Fame this year after a 15-season career with the Astros in which was the NL Rookie of the Year in 1991 and NL MVP in 1994. He doesn't work for the team full-time, but is spending a few days at camp this spring to help out, particularly with the first basemen.

''Just get acquainted with them, give them what I think can help a little bit,'' he said. ''It's a great opportunity they need to take advantage of it.''

Singleton is embracing his time with one of the Astros' greats.

''He has a lot to teach,'' Singleton said. ''There's a lot to learn from. Everything he did he was good at it. So whenever you can pick up little bits of information, it's great.''

Bagwell believes first base is an interesting position because he says it's easy to be adequate but extremely difficult to be great. He shared what he thinks makes a great first baseman.

''Just being involved,'' he said. ''The first thing is you just got to catch the baseball, which sounds very stupid, but it's true. There's nothing worse than a first baseman dropping the ball. Other than that you've got to be athletic in bunt plays and take care of your infielders. Whether that means picking balls out of the dirt or just moving around, have communication with your second baseman to make sure you know where they are. Just little things go a long way to be a great first baseman.''

Singleton added intensity to his workouts this offseason and added about 25 pounds of muscle to his 6-foot-2 frame. He said no one from the team has taken him aside to impress upon him the about what's at stake this spring. But he knows what they expect and says he's ready for the challenge.

''I would love to be the everyday first baseman,'' he said. ''I've just got to continue to go out and work hard and prove to them that I am the man for the job. Just be more consistent throughout everything, defense, hitting, with all aspects of the game.''