MILWAUKEE -- After slumping their way into the All-Star Break, the Chicago Cubs seemed to have regained their mojo, winning four of their last six games.

Starting pitching has been a big factor in that stretch; Chicago's rotation has combined for a 1.54 ERA.

Jason Hammel will try to keep that going Friday when the Cubs travel north to Milwaukee where they will open a three-game series against the Brewers at what's expected to be a heavily-partisan crowd at Miller Park.

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Hammel snapped a four-decision losing streak in his last start, holding the Texas Rangers to a run on three hits over six innings in a 3-1 Cubs victory last Saturday in Chicago.

He credited the turnaround, oddly enough, to potato chips.

"(Team doctor Stephen Adams) called me over the break and told me again today, 'potato chips.'" Hammel said, "My prescription is potato chips, which blew me away because I've never heard of a doctor that said potato chips."

The reason for the snaky treat wasn't superstition; Hammel has been plagued at times during his career by cramps and dehydration, so Adams suggested turning to potato chips to boost his potassium levels.

"I think it turned out well," Hammel said.

He's faced Milwaukee once in 2016, allowing four runs over six innings in a 5-3 loss at Milwaukee on May 19 but is 8-1 with a 2.66 ERA in 12 career starts against the Brewers and 5-1 with a 2.18 career ERA in eight starts at Miller Park.

Right-hander Jimmy Nelson will make his 20th start of the season for the Brewers.

Nelson snapped mid-summer swoon with seven strikeouts over scoreless innings against the Reds his last time out. In seven previous starts, Nelson had gone 0-4 with a 5.14 ERA.

"It felt good to be back to where I was early on," said Nelson, who started the season 5-3 with a 2.88 ERA before his recent slide. "My pitches seemed to have better life on them."

Nelson worked on some adjustments to his delivery during the All-Star break and they seemed to pay off against the Reds. It also didn't hurt that the Brewers, who have struggled at times to put runs on the board, jumped out to an early lead which allowed Nelson to settle in.

"It's helpful," Brewers manager Craig Counsell said. "I don't want to say relaxing, but it's a better way to go through a game."

Nelson will be looking for his first career victory against the Cubs. He's faced them nine times in his career, including seven starts, going 0-4 with a 2.83 ERA.

He's faced the Cubs one this season, throwing 7 1/3 scoreless innings while scattering five hits and four walks with five strikeouts in a 2-1 loss May 18 at Miller Park.

The Brewers have struggled since the break, dropping series to the Reds and Pirates, and are 6-13 in their last 19 games with a 7-8 mark in their last 15 games at Miller Park.

Against the Cubs this season, the Brewers are 2-3. Chicago has gone 25-13 against Milwaukee since the start of the 2014 season and has won six straight series including three straight and four of the last five at Miller Park.