Millwood left a strained left patella tendon after making four warm-up pitches before the seventh inning. He is not expected to miss a start.
"It's only tendinitis," Millwood said. "I've had that for a while. It comes on and then goes away. With tendinitis, you never know."
Millwood is 7-8 this year with a 4.75 ERA this season after going 18-7 with a 2.68 ERA in 1999.
The Braves, who completed a three-game sweep, went ahead 1-0 when Andres Galarraga hit his 24th homer with two outs in the fourth. The Braves are now 21-2 when Galarraga homers.
After the Padres tied it in the eighth when Terry Mulholland walked pinch-hitter Desi Relaford with the bases loaded, the Braves went back ahead with three runs in the bottom half thanks to three hit batsman.
After intentionaly walking Chipper Jones, Walker then hit B.J. Surhoff to load the bases. Heathcliff Slocumb came in and hit Galarraga with a pitch to make it 3-1. Brian Jordan followed with a sacrifice fly.
"I've never seen that, but in this game you never know," Jordan said when asked about having three teammates get hit in one inning. "I'm just glad we could hang in there and pull it out."
Scott Kamieniecki (2-1) got one out for the win, and John Rocker pitched the ninth for his 16th save and second in as many games.
Millwood, who has not missed a start since joining the Braves' rotation in 1997, walked one and struck out eight.
Manager Bobby Cox and trainer Jeff Porter first came on the field and spoke with Millwood with two outs in the sixth and the count 2-0 on Mike Darr. Pitching in 95-degree heat, Millwood remained in the game after walking Darr and getting Ryan Klesko to pop up to right field. He then left before starting the seventh.
"There's nothing seriously wrong with him," pitching coach Leo Mazzone said. "He's pitching as well as he has all year."
Galarraga, whose three-run homer Tuesday accounted for all of Atlanta's runs, hit a solo shot off Adam Eaton with two outs in the fourth. Eaton gave up one run and four hits in seven innings.
"I wish I could take back that pitch I threw to Galarraga," Eaton said. "It was a hanger. It was on the corner, and he had to extend to get it. It was a good pitch. He one-handed it out."
©2000 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed