Locke, who has been in the rotation since joining the big league team on Sept. 6, will be limited to about 75-80 pitches in the outing. He has maxed out at 82 in his first three starts, none of which have lasted more than five innings.
Locke last pitched on Friday, meaning that he will take the mound on a normal four days of rest. He allowed one earned run on six hits in 4 2/3 innings in that start against the Reds.
Charlie Morton and Ross Ohlendorf will start the first two games of the series. The Pirates are still looking for their first win at Miller Park this season. The last Pittsburgh starting pitcher to win a game in Milwaukee was Tom Gorzelanny on May 3, 2007.