SAN FRANCISCO (AP) -- Brandon Phillips and Jay Bruce homered off San Francisco' Matt Cain and the Cincinnati Reds led the Giants 3-1 after six innings of their NL division series opener Saturday night despite losing ace Johnny Cueto to a back injury after eight pitches.
Cueto had the shortest postseason start in the majors in eight years when back spasms forced him to leave while pitching to the second batter of the game. He is day to day.
Reliever Sam LeCure and scheduled Game 3 starter Mat Latos held the Giants scoreless until Buster Posey's leadoff homer off Latos in the sixth cut Cincinnati's lead to 3-1.
Cincinnati had taken the lead on Phillips' one-out home run in the third inning that also scored Drew Stubbs. Bruce added a solo shot in the fourth.
Those were the first earned runs Cain had ever allowed in the postseason, ending a run of 23 1-3 straight innings without an earned run that was the fifth-longest ever. It was also just the second time the past two seasons that Cain allowed two homers in a game at home with the other on June 29 against Cincinnati.
The Reds were looking for their first postseason win since 1995, having lost seven straight since then in the 1995 NLCS to Atlanta and the division series two years ago to Philadelphia.
If Cueto's injury isn't serious, he could come back and take Latos' spot in the rotation in Game 3. If he can't come back, that could be a big blow to the Reds. His 2.58 ERA the past two seasons is third best in the majors and Cincinnati had to rely heavily on Latos and the bullpen in the opener of the best-of-five series.
The Reds ran to the NL Central title based on the health of their starting pitchers. None of their five starters got hurt all season and they only needed a sixth starter when Todd Redmond started the back end of a doubleheader in August against the Cubs.
Cueto struck out Angel Pagan to open the game but appeared as if he might have aggravated something when stopping mid-motion when Pagan called time out earlier in the at-bat.
Cueto then pulled up lame on the second pitch to Marco Scutaro and Baker and a trainer rushed out to the mound to check on the 19-game winner, who left the game.
Cueto's outing was the shortest start in the postseason since Atlanta's John Thomson also only retired one Houston batter in Game 3 of the 2004 NLDS. He threw just four pitches before leaving with a sore muscle in his left side.
LeCure relieved and retired the first four batters he faced before loading the bases with two outs in the second. He escaped that jam by getting Cain lined out to right field.
Latos, pitching on three days' rest, came in to start the third and didn't allow a run until Posey's homer. He was helped in the fourth when Joey Votto caught a hard liner by Brandon Belt to start an unassisted double play after Hunter Pence reached on a throwing error by third baseman Scott Rolen.
After 49ers quarterback Alex Smith one-hopped the ceremonial first pitch to Giants reliever Sergio Romo, Cain picked up where he left off in the 2010 postseason when he didn't allow an earned run in three starts.
Cain pitched a perfect first inning, getting help when Belt flipped head over heels over the railing in foul territory near first base to catch a popup from Zack Cozart for the second out. Cain struck out Votto to end the first inning. Cain pitched around a one-out double to Bruce in the second inning before running into trouble in the third.
His night ended after five innings when he left for pinch-hitter Aubrey Huff. Cain allowed three and five hits with four strikeouts.