"He went eight innings last time out," Marlins manager Don Mattingly said. "We wanted to give him the extra day."
Fernandez pitched eight frames in Tuesday's 1-0 home win over the Nationals. The Marlins' ace gave up just three hits and struck out 12 without walking a batter. He was in complete control, retiring 21 straight batters during one stretch.
The 24-year-old right-hander is 16-8 with a 2.86 ERA in his first full season back from Tommy John surgery, which was performed in May 2014. He was on a plan to throw around 180-190 innings this season, and he is still going strong with 182 1/3 frames logged so far in 2016, with 253 strikeouts.
Fernandez's 12.49 strikeouts per nine innings are the best in the Majors, and he's also first in strikeouts per batters faced, with a .343 percentage.
By pushing him back a day, it also puts Fernandez on schedule to start the final game of the season. If the Marlins are eliminated from postseason contention, Fernandez would not make that start.
"If we need him, then we have him, and if not, we don't have to worry about it," Mattingly said.
Adam Conley gets the start on Sunday in place of Fernandez. The lefty will be coming off of the 15-day disabled list with tendonitis in his left middle finger and isn't expected to pitch deep into the game.
Conley threw a 35-pitch, three-inning simulation game on Wednesday, and Mattingly said he would be happy if Conley, who has been on the DL since Aug. 14, could go that far on Sunday.
The plan behind Conley's start is simply to get him back on the mound before the end of the season, and this provided an opportunity to do so.
"Not very far," was Mattingly's comment on Conley's duration. "We wouldn't be able to do this if we didn't have a bullpen with three long guys in it and basically three starters in it. [Conley's start] will be fairly short."
Glenn Sattell is a contributor to MLB.com based in Miami.