MIAMI -- Highly regarded prospect Jazz Chisholm was declared the winner of the spring competition for the Miami Marlins' second-base job on Sunday, and he'll be in the lineup on Opening Day.

Chisholm batted .268 with three homers and four stolen bases in spring training.

He was competing with Isan Diaz for the Marlins' only open every-day job and won almost by default. Diaz went 2-for-34, and he will start the season in Triple-A.

Manager Don Mattingly and general manager Kim Ng told Chisholm shortly before the final spring training game that he was heading south with the team.

"It feels great when everybody believes in you," Chisholm said. "I know I already have a lot of confidence, but it gives you confidence to where it's almost cockiness."

In 2020, Miami second basemen had an OPS of .602, last in the National League. Chisholm made his big league debut in September and went 9-for-56 (.161).

Chisholm, 23, came to Miami in the 2019 trade that sent pitcher Zac Gallen to the Arizona Diamondbacks.

"We look at Jazz as the every-day second baseman," Mattingly said. "But this is the start of it. You've got to go perform and keep going every day."

The young Marlins finished 14-5 in spring training, best in the majors. They're trying to build on an unexpected run to the playoffs last year, and they open the season on Thursday against the Tampa Bay Rays.

"I'm happy with the club," Mattingly said. "In general, we have played pretty good baseball."