Medlen looks to continue his dazzling stretch, as the Braves attempt to build on a rare offensive outburst and solve Lee at home for the first time in over two years Friday night.
Atlanta (94-65) has already clinched an NL East title, but has sputtered through September with an 11-13 record while batting .223.
The Braves are hoping they've become untracked following Thursday's 7-1 victory, scoring all of their runs in the first two innings of the opener of this four-game set. They also collected 12 hits with a homer and six doubles.
"It is good to get hits," said Jason Heyward, who had a career-high five hits, including a home run and three doubles. "Good to get on base and get the game going early."
Medlen (14-12, 3.24 ERA) is well aware of Atlanta's recent offensive issues, but he's 4-0 with a 1.03 ERA in his last five games. That includes winning all three home outings behind a 0.42 ERA.
The right-hander was let down by the lineup Saturday, when he yielded one run in 7 1-3 innings in a 3-1 defeat to the Chicago Cubs.
Medlen has won his last two starts versus Philadelphia (72-87) with a 3.46 ERA, and another victory could give the Braves sole possession of the best record in the NL.
They're tied with NL Central-leading St. Louis with three games left in the regular season. Atlanta won the season series, giving it the tiebreaker if the teams finish tied for the best record.
"Right now, we're playing for home-field advantage, and home is where we would like to be for the most part of our series," Heyward told the team's official website.
Lee (14-7, 2.93) may also enjoy being at Turner Field, where he's won three straight starts behind a 0.86 ERA since taking a loss in 2011. The left-hander has tossed 19 consecutive scoreless innings over that stretch, with eight coming with eight strikeouts in a 2-0 victory April 4.
Lee is 4-1 with a 2.12 ERA and 58 strikeouts in 51 innings over his last seven starts. He was the hard-luck loser Sunday, allowing three runs while fanning eight in seven innings of a 4-3 defeat to the New York Mets.
He'll conclude the season as the Phillies' leader in wins and strikeouts (209), and the lowest ERA of a starter.
"I feel like I did OK," Lee told the team's official website. "I made it basically all year without really getting injured. I was able to take the ball and give the team a chance to win more times than not. As a starting pitcher that's my job, so I've got to feel pretty good about that."
He may also feel good about facing Heyward since he's held him to 3 for 19.
Jimmy Rollins, 3 for 4 with a double in the series opener, has a .355 average (11 for 31) over seven road meetings with the Braves this year. However, he's just 2 for 11 versus Medlen in 2013, while Domonic Brown is 4 for 9 with a homer and triple.