As a result, Maholm will make the start in the final game of the Pirates' opening season series in Atlanta, while Morris and Duke will take the mound in the team's first two games against the Marlins.
Russell had announced early last week that Snell would get the March 31 Opening Day start and that Gorzelanny would get the home opener nod in Pittsburgh a week later.
With the rotation set, pitching coach Jeff Andrews has finalized the final week of Spring Training for each of the team's starters. Saturday's rain-shortened game vs. the Rays threw a crux in Andrews' original schedule for his staff, but in the end, the rainout actually helped set some of the schedules in place.
On normal rest, Gorzelanny would have been scheduled to pitch his final Grapefruit League game on Wednesday. However, since he will not be pitching in his first regular-season game until the following Wednesday, Andrews wanted to push the left-hander's start back a day.
"I didn't want him having a week off in between," Andrews said.
So with Gorzelanny now starting on Thursday, Duke, who threw just two innings on Saturday, will make his next start on Wednesday. He is targeted to throw between 80-90 pitches.
Duke will then stay in Bradenton once the team leaves for Atlanta on Saturday evening, and he'll throw about 35-40 pitches at Pirate City before rejoining the team. That will give Duke five days' rest between his final tuneup and his first regular-season start.
The rainout and rescheduling also benefits Maholm, who was originally slated to throw 85-90 pitches at Pirate City on Friday. That would have meant that his start on Sunday against the Yankees would have been his last Grapefruit League appearance this spring.
But with Duke now able to start Wednesday's game (instead of on Friday as originally planned), Maholm will now be able to start the team's game against the Twins on Friday.
John Grabow, Evan Meek and Phil Dumatrait -- all of whom were supposed to pitch in one of the Pirates' Grapefruit League games this weekend -- instead each threw over at Pirate City due to Saturday's rainout. Dumatrait, who the Pirates are looking at as a long reliever for the bullpen, threw 40 pitches, while Meek and Grabow each threw about half that much.
Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.