The Nationals, who beat the Marlins 10-3 on Thursday in the opener of the four-game series, are 51-51. The Marlins are 44-60.
Scherzer, 33, has made 16 career starts against the Marlins, posting a 9-3 record with a 3.51 ERA, 9.6 strikeouts per nine innings and a 1.081 WHIP. In eight career starts at Marlins Park, Scherzer is 5-2 with a 2.54 ERA.
This year, he is 2-0 with a 5.54 ERA in two starts against Miami.
Scherzer got off to a great start this year with a 10-1 record. He then ran into a tough patch, losing four straight decisions. But during that five-game stretch, including one no-decision, Scherzer was still solid.
Perhaps the biggest difficulty for Scherzer this year was the dugout altercation he had with fellow Nationals pitcher Stephen Strasburg on Friday.
"Look, it was a miscommunication," Scherzer told The Washington Post after the spat was caught by television cameras. "It's over, settled -- end of story."
Nationals manager Dave Martinez said he spoke to both pitchers after the incident.
"These things happen," Martinez told The Post. "I've been on teams where guys want to choke each other."
While the Nationals -- in the midst of a disappointing season -- bicker among themselves, the Marlins have emerged as a young and improving team.
Miami's team batting average and OPS have improved every month this season. And Lopez -- who at age 22 is more than a decade younger than Scherzer -- has made major strides this year.
Lopez started 2018 at Double-A Jacksonville and was quickly promoted to Triple-A New Orleans. He posted an impressive 1.44 ERA in 12 starts at the two stops.
In the majors, Lopez has made four starts, allowing 10 runs in 11 innings in his second and third appearances. In his other two starts, however, Lopez has been much better, allowing three runs in 12 innings.
Lopez beat the New York Mets 5-2 in his major-league debut, allowing two runs in six innings in that game.
"I'm extremely happy with the way it went," Lopez said after beating the Mets. "It is something I will cherish for the rest of my life."
Beating Scherzer -- if Lopez can accomplish that on Friday -- would be another memorable moment for the pitcher who was acquired from the Seattle Mariners last year in the trade for veteran David Phelps.
Rendon, who was placed on paternity leave Thursday, and his wife, Amanda, are set to welcome the birth of their first child this week.
Matt Reynolds was recalled from Triple-A Syracuse and started at third base on Thursday, replacing Rendon, who is batting .284 with 15 homers and an .861 OPS.
Harper sat out Tuesday's game against the Atlanta Braves because of a stomach virus, but he tied the National League lead with his 25th homer on Wednesday.
"I felt OK," Harper told mlb.com after his homer, "but it's going to take a couple of days (to fully recover), for sure."
Harper went 1-for-4 with an RBI double and a walk on Thursday. He also struck out three times, however.
Another key Nationals hitter, Daniel Murphy, is questionable for Friday. He sat out Thursday's start because of a sore knee, although he had a pinch-hit double in the eighth inning.