"That was my goal, to finish strong. I wanted to start fresh and just work hard," Doubront said. "I needed to have more success in this last start."
Twins right-hander Phil Hughes took the loss, going 5 1/3 innings, giving up four runs on 10 hits and a walk with two strikeouts.
The Red Sox scored two runs in the fourth when Napoli walked with one out and scored on Mike Carp's two-out double. Xander Bogaerts' single scored Carp.
Napoli, who went 1-for-2 with two runs scored and an RBI, opened the sixth with his fourth Grapefruit League home run. Consecutive one-out singles by Carp, Ryan Dent and Derrik Gibson gave the Red Sox a 4-0 lead.
In his first two Grapefruit League outings, Doubront went a combined six scoreless innings, giving up just three hits. In his next two, though, he went eight innings, giving up 15 runs on 20 hits. Against the Twins Friday afternoon, he managed to pitch himself out of trouble. In the fifth, after giving up leadoff hits to Aaron Hicks and Eduardo Escobar, Doubront struck out Pedro Florimon, Jason Bartlett and Joe Mauer to end the threat.
"We want a little bit more efficiency, but he made a number of good pitches that were elusive for him the last time out," said Red Sox manager John Farrell.
Hughes, who is beginning his first season with the Twins after joining the team as a free agent in December, was making his fifth start. Over 19 innings, he's surrendered 12 runs (10 earned) on 26 hits and four walks with 12 strikeouts.
Up next: Right-hander Jake Peavy will make his third start on Saturday when the Red Sox host the Twins at 1:05 p.m. ET in the teams' final Grapefruit League game. Peavy has made just two starts this spring after being delayed when he cut his left index finger with a fishing knife on March 1. In his previous outings, spanning 7 2/3innings, he has given up two earned runs on six hits and three walks with seven strikeouts for a 2.35 ERA.
Maureen Mullen is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.