That was before the Angels rallied in the top of the seventh, scoring four times to go ahead on Gary Matthews Jr.'s two-run single, then adding key runs in the eighth and the ninth to beat the Boston Red Sox 7-5.
"It was awesome to be able to come back like that at Fenway Park," Saunders said. "It's a big confidence boost."
Saunders (4-0) gave up three runs on seven hits and three walks, striking out three.
Playing the team that swept them out of two of their last three playoff appearances, the Angels won two out of three. They took a 5-3 lead in the seventh off three Red Sox relievers who gave up four singles and three walks.
A day after hitting two solo homers, Matthews had three hits and three RBIs. He hit a two-run single to break a 3-3 tie in the seventh, then made it 6-3 with an RBI double in the eighth - a run that proved important after David Ortiz hit a two-run homer with two out in the ninth.
"We're swinging the bats much closer to what we expected than we did in the playoffs last year," Angels manager Mike Scioscia said. "When we are playing well, we can play with any team that's out there. It's just a matter of bringing that game on a daily basis. We weren't able to do that last year."
Scot Shields pitched a perfect eighth, then gave up Ortiz's homer. Francisco Rodriguez got Manny Ramirez on a deep fly to center to end the game and earn his ninth save.
Javier Lopez started the seventh and did not record an out, then Manny Delcarmen (0-1) had the identical line with two runs allowed on one hit and one walk.
"It got away in a hurry," Red Sox manager Terry Francona said. "We were trying to piece together the seventh, ... and it didn't work from the very beginning."
Mike Napoli hit homer No. 5; last year, he didn't hit his fifth until May 23.
Ramirez had three hits for Boston, and Coco Crisp returned from two weeks of hamstring problems to hit two doubles and steal third both times.
The collapse of the Boston bullpen deprived emergency fill-in Justin Masterson of a victory in his major league debut. After scratching starters Josh Beckett (neck) and Daisuke Matsuzaka (flu) in consecutive days and moving Thursday's pitcher Jon Lester to Wednesday, the Red Sox called up Masterson for his first outing above Double-A.
The 23-year-old Masterson is the first Jamaican-born player to pitch in the majors, the Red Sox said. He allowed one run on two hits and four walks in six innings while striking out four, but wound up with a no-decision.
"Masterson came in today out of the blue for a call-up and threw us six great innings," Delcarmen said. "I came in, first and second, and wanted to get in there and try to get out of it, and it didn't happen today."
Kevin Youkilis also returned to the Boston lineup after missing a game with a lower back problem. Add a potential knee problem to his woes: He ran into the rolled up tarp when chasing after a foul popup in the seventh, but stayed in the game.
Notes: To make room for Masterson, reliever Craig Hansen was sent back to Triple-A Pawtucket. ... Boston 3B Mike Lowell was headed for a weekend of minor league rehab in Pawtucket. ... Beckett threw on the side and is on track to start Sunday. Matsuzaka might not make the trip to Tampa Bay because of his illness. ... Ramirez picked up a double in the seventh when center fielder Torii Hunter gloved his deep fly, but dropped it after colliding with Matthews. ... Kevin Cash, subbing for flu-ridden Boston C Jason Varitek for the fourth straight game, doubled. ... The Red Sox said after the game that they will purchase the contract of Bryan Corey from Pawtucket on Friday to take Masterson's spot on the roster.