Before having to attend to a personal matter in his native Dominican Republic, Marte was batting .380 with eight RBIs in 11 games and hit safely in the first 10 before going 0 for 4 in Friday's 6-3 loss at Wrigley Field.
With Marte away, Harrison moved into the No. 2 spot Saturday and went 2 for 4 with three RBIs in a 5-3 victory against the team that drafted him in the sixth round in 2008. Marte is expected to return for Monday's series opener in Tampa Bay, and Jose Tabata could make another start in his place Sunday.
"You never want anybody to have to get away, but we got a very capable Plan B that just turned into Plan A," manager Clint Hurdle told the team's website about Tabata.
Gregory Polanco extended his career-opening hit streak to 11 games after he was awarded an infield single on a replay review in the seventh inning Saturday. Harrison followed with a two-out homer, his fifth of the season and first in 16 games.
Polanco, batting .365, is the first NL player to begin with an 11-game hit streak since Juan Pierre hit safely in his first 16 for Colorado in 2000.
Polanco will try to move closer to Pierre's mark while leading the Pirates (36-38) to their third victory in four games and helping Cumpton (2-2, 5.82 ERA) gain a third consecutive win.
The rookie right-hander earned the latest of those victories June 11 against Chicago (31-41), allowing two runs over five innings in a 4-2 win. He gave up three runs in six innings against Cincinnati on Tuesday and did not get a decision in a 6-5 loss.
Cumpton will again pitch opposite Jason Hammel (6-4, 3.02), who hasn't been very effective in his last two outings. The Cubs right-hander went 0-1 with a 6.55 ERA in those games and allowed a combined 23 baserunners after registering a 0.88 WHIP in his first 12 starts.
Hammel yielded a season-high 11 hits, four runs, two walks and hit a batter over five innings in his loss to Cumpton. He was 4-0 with a 2.70 ERA in his prior four matchups versus the Pirates, including 2-0 with a 2.63 ERA in his first two this season.
"Honestly, I thought I did a pretty good job for as many baserunners as I had," he said after the loss to the Pirates. "It was definitely a battle. It was a grind. You've just got to keep pitching, keep throwing strikes."
Hammel allowed another four runs and eight hits over six innings Monday in a 5-4, 13-inning victory, but he also struck out a season-high nine.
Cumpton got his only career hit off Hammel earlier this month, and Polanco singled in his second career game. Jordy Mercer is 3 for 7 versus the right-hander this season.
Luis Valbuena had three of the Cubs' five hits against Cumpton on June 11.