Griffey became the youngest player in baseball history to reach 400 home runs and had the added satisfaction of accomplishing the feat on his father's birthday, but it came in a losing effort as the Colorado Rockies won their home opener, 7-5, over the Cincinnati Reds.

Griffey recorded the milestone hit with with none on and one out in the fourth inning, sending a 2-0 pitch from Rolando Arhoho over the left-field wall. Griffey reached 400 homers at 30 years, 141 days old. Jimmie Foxx hit his 400th career homer at 30 years, 248 days.

"I think the first couple of times I came here I tried to hit home runs and I ended up going back to the dugout," said Griffey, who entered the game hitting .350 with three homers and eight RBI at Coors Field. "I just tried to hit it hard. I don't have any idea what it was."

The home run was a perfect gift for his father, Ken Griffey Sr., a bench coach on the Reds who celebrated his 50th birthday today. It was the fourth time in Griffey's career that he homered on his dad's birthday.

Griffey became the 27th player in baseball history to hit at least 400 homers. Acquired in an offseason trade from Seattle, the future Hall of Famer has two homers this season but is batting just .138 (4-for-29) through eight games.

Mike Lansing and Todd Helton did their best to try to overshadow Griffey, each belting two-run homers for the Rockies, who scored four times in the fifth to build a 5-1 advantage.

Arrojo (1-0) was more than up to the challenge in his first start at Coors Field, one of the toughest ballparks in the majors to pitch in. The righthander allowed two runs and six hits with no walks and four strikeouts. He left after the sixth with a contusion on the middle finger on his right hand.

Rookie D.T Cromer hit his first major league homer, a three-run shot with two out in the ninth inning off David Lee , to bring the Reds within the final margin.

Former Red Stan Belinda struck out Chris Stynes with a runner on second and two outs in the ninth for his first save.

"We played well. It got a little tight at the end but that's the Coors Field factor," Colorado manager Buddy Bell. "Overall it was a good day. We came up with some big hits, but Arrojo really got us going."

Reds starter Steve Parris(0-2) was tagged for five runs and eight hits in four-plus innings. He walked two and struck out five.

Arrojo got the winning rally started for Colorado in the fifth with a leadoff single. Tom Goodwin knocked him in with a triple and Lansing followed with his third homer, giving the Rockies a 4-1 advantage. Darren Bragg delivered a run-scoring single later in the inning off Hector Mercado.

"It was a good win for us, coming off a tough road trip," Lansing said. "It's still early but everytime I step up to the plate I feel more confident. I'm just trying to get good pitches to hit. I'm not a home run hitter."

The Reds got a run back in the sixth. Consecutive singles by Alex Ochoa, Stynes and Barry Larkin loaded the bases with none out.

But Arrojo was able to avert any real damage. Griffey lofted a sacrifice fly before former Rockie Dante Bichette bounced into a 1-6-3 double play to end the inning. Arrojo suffered the injury on that play when the ball hit his finger.

Helton gave the the Rockies a 7-2 lead in the seventh with a two-run homer off Steve Sullivan.