All the Brewers runs in the third against Iglesias were unearned after Phillips' fielding error on Gennett's grounder near second base. A Carlos Gomez RBI double and bases-loaded bloop single by bench candidate Luis Jimenez made it a 6-2 game.
Iglesias finished with three of his six runs allowed being earned over four innings with five hits, two walks and four strikeouts. He has a 3.68 ERA through six games, including three starts.
"At the beginning of the game, I was actually feeling really well," Iglesias said through translator Tomas Vera. "But little things that I have to continue to address and little things I have to get better at improving. Other than that, it's baseball. That's the way it is."
In his fifth start of camp, Brewers starter Matt Garza finished with five earned runs and seven hits allowed over 5 2/3 innings. He walked one and struck out six.
Garza gave up four straight hits to start the bottom of the first inning, with Phillips' two-run double off the right- center-field wall bringing Cincinnati to within one run. Garza would retire the next 11 in a row, including ending the first with a ground-ball double play by Jay Bruce.
"I feel good and I'm not completely crisp, but I know what I need to work on and it's not a huge difference, it's more of a fine-tuning," said Garza, who threw 90 pitches. "Now it's more getting a feel for game speed, the atmosphere and trying to slow it all down and get ready for game two [of the regular season]."
Cincinnati added three more runs in the fifth inning against Garza on an RBI single to center field by Joey Votto in his 2-for-3 game and a Phillips two-run double to left field.
Up next for the Reds: With Mike Leake working a Minor League game, the Reds are using a slate of relievers to face a Cubs split-squad game Saturday at 4:05 p.m. ET in Goodyear. Leading the way with a rare start will be closer Aroldis Chapman, who will appear for the seventh time this spring. Manny Parra, Tony Cingrani and Nate Adcock are also slated to pitch. Third baseman Todd Frazier, who hit in Minor League games on Friday, will likely return to the lineup as well. The game can be heard live on Gameday Audio.
Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.