CINCINNATI (AP) -- Barry Bonds watched from the dugout as his rookie fill-in made a little history.
With Bonds getting a break in his pursuit of Hank Aaron's home run record, his replacement got a chance to crack the record book. Lewis became the first San Francisco rookie to hit two grand slams in a season.
"I'm speechless," Lewis said, with a look of wonder on his face. "I was very emotional at that point in time."
Bonds got the day off following a night game, leaving him with 751 career homers -- four shy of Aaron's mark. He's expected to play in the final game of the series Thursday, then perhaps all three in St. Louis before the All-Star break.
Only 24,092 fans attended the holiday game, showing a lack of enthusiasm for Bonds' chase of a revered record. Fans booed and derided Bonds as a cheater -- references to baseball's steroid scandal -- while he rounded the bases after hitting No. 751 on Tuesday night.
On Wednesday, a 26-year-old rookie took Bonds' spot in left field and measured up. Lewis had three hits, including a fourth-inning grand slam off Matt Belisle (5-6).
No one missed the irony.
"We were joking around on the bench," Lewis said. "The trainer was like, 'C'mon, Barry.' And I was like, 'Oh, yeah, I am Barry today. I'm playing left field."
Lewis didn't hit a homer during a September call-up last year. Two of his three homers this year are grand slams, a hint of what might be ahead for a player just getting started.
"He's got a lot of tools to work with," said Rich Aurilia, who also hit one of the Giants' four homers. "He's still learning baseball. I don't think he's developed his power yet. It's nice that he came up with the big hit today."
No one appreciated it more than Cain (3-9), who got his first win since May 13. The right-hander has been the Giants' hard-luck pitcher -- the bullpen had blown three leads for him, and the offense had scored only three runs in his last 32 innings on the mound.
The Reds trailed 3-1 when Aurilia beat out an infield single to load the bases and bring Lewis to the plate.
"I felt something was going to happen," said Cain, who gave up four runs in 5 2-3 innings. "It was weird. I just had a feeling, after Aurilia got that infield hit, like things were going to go our way."
Ray Durham, Aurilia and Mark Sweeney hit solo homers for the Giants, who sent the Reds to their first loss in two games under interim manager Pete Mackanin. Sweeney's shot in the ninth was his 15th pinch-hit homer, tying Dave Hansen for seventh on the career list.
Mackanin got to experience a meltdown by a pitching staff that was one of the reasons manager Jerry Narron got fired on Sunday.
"You see potential, you see good arm strength," Mackanin said. "You see guys who are on the fence, and you're waiting for somebody to fall on the right side, and they keep falling on the wrong side."
A fast-moving storm delayed the game for 51 minutes in the middle of the eighth inning. Gusting wind repeatedly blew the tarp away from the grounds crew while it covered the field.
With no baseball to worry about, Bonds got to spend some time with an old pal.
As part of a team function, the Reds and their families played on the field before the game. Bonds went out in his gray uniform pants and a black Giants T-shirt and sought out Griffey.
The two have felt a kinship throughout their careers. Both had famous fathers who took them into clubhouses when they could barely walk. Bonds played mentor to Griffey when Junior was just getting started on his career.
The bond was evident.
Bonds shared a belly laugh with Griffey and his wife, and playfully hoisted Junior's 5-year-old son in his arms. It was a special moment for the two outfielders, who will have another one next week in San Francisco, when they start side-by-side in the All-Star game.
Once they got done socializing, one of them got down to business.
After Bonds hit a two-run homer in the series opener on Friday night, he declared that he was up 1-0 in their head-to-head competition. A day later, Griffey matched his RBIs with a less-dramatic swing -- a two-run single that put the Reds up 3-0 in the third.
Griffey remained at 585 career homers, one behind Frank Robinson for sixth on the career list.
The Giants put left-handed reliever Jonathan Sanchez on the 15-day DL with strained muscles in his side. Sanchez felt sore when he warmed up Saturday and hadn't pitched since. RHP Scott Atchison was called up from Triple-A Fresno to take his place. ... Aurilia made his first start since he returned from a stint on the DL with a sore neck. ... SS Omar Vizquel committed his fifth error of the season. ... The Reds have given up five grand slams this season. ... The Reds haven't won a series since they took two of three from Cleveland at Great American Ball Park from June 8-10.