SAN FRANCISCO - Adam Dunn hit two homers and Felipe Lopez added a go-ahead two-run shot in the sixth, leading the Cincinnati Reds to an 8-7 victory over the San Francisco Giants on Wednesday night.

Sean Casey had three hits and Juan Castro doubled home a late run for the Reds, who blew a big early lead but rallied for just their second victory in 13 games.

Dunn hit his 30th and 31st homers off Brett Tomko to move into second place in the NL behind Philadelphia's Jim Thome. He connected for a three-run shot in the third inning and a solo homer in the fifth, but San Francisco tied it with a four-run rally in the fifth.

The Reds got a much-needed victory, but also got another scare. Ken Griffey Jr. went 2-for-3 with his 400th career double in his first appearance since tearing his hamstring on July 10, but the veteran Cincinnati slugger left in the fifth inning with stiffness in his hamstring.

Pinch-hitter Dustan Mohr hit just the second inside-the-park homer in the ballpark's history, but Tomko and his relievers struggled in San Francisco's fifth loss in seven games.

Josh Hancock (2-1) got two outs for his second victory in Cincinnati since arriving in a trade with Florida on Friday.

The Reds went ahead when Lopez got just his second homer of the season off Scott Eyre (0-2). San Francisco got a run back when a fan in the left-center stands stuck out his mitt to catch J.T. Snow's drive to the wall, sending Deivi Cruz home from first base on the ground-rule double.

Javier Valentin tripled and scored on Castro's double in the seventh. Cincinnati's lead shrank to 8-7 when Ray Durham homered in the eighth, but Gabe White got Barry Bonds on a weak inning-ending grounder.

In the ninth, Danny Graves walked A.J. Pierzynski and Marquis Grissom hit an infield single - both with one out - before striking out pinch-hitter Ricky Ledee and getting Edgardo Alfonzo on a groundout for his NL-leading 35th save in 43 chances.

Bonds went 1-for-3 with two walks, including his 98th intentional pass of the season.

Cincinnati starter Jose Acevedo blew a four-run lead in the fifth to remain winless in eight straight starts, allowing eight hits and five runs in 4 2-3 innings.

But Tomko allowed 10 hits and five runs in five shaky innings. He also stayed in in the third after narrowly deflecting Casey's line drive before it hit him in the head.

In the fifth, Mohr's long fly to the wall ricocheted off Dunn's glove and rolled to the home bullpen down the left-field line - and Mohr never stopped sprinting on the way to a headfirst slide at home.

Two outs later, Bonds scored on Wily Mo Pena's error to cut Cincinnati's lead to 5-4. Pierzynski then singled home Pedro Feliz with the tying run, but Pena ended the inning by throwing out Pierzynski at the plate on Neifi Perez's single.

Notes: SS Barry Larkin will return to the Reds' lineup Friday in Colorado. He hasn't played since late last month, when he strained an oblique muscle. … It was Dunn's fifth two-homer game of the season, and the ninth of his career.