DENVER (AP) -- The grimace on Barry Bonds' face told the story just seconds before he fell to the ground in pain.

Two innings after hitting an upper-deck home run, the eight-time All-Star left the field with a lower back injury in the ninth inning of San Francisco's 10-9 loss to the Colorado Rockies on Saturday.

	Bonds

"No answers," Baker said. "The doctors don't even have any answers, so how can I have any answers? ... He ain't going to play (Sunday). I know that."

Bonds, tied for the major league lead with 15 homers, grimaced as he hit a ground ball to second and got three steps out of the batter's box before falling to the ground.

He remained flat on his stomach for several minutes before waving away a stretcher as he was helped to his feet. Bonds ultimately was taken from the field on the back of a maintenance cart.

"I knew it was something," Baker said. "When I got out there, he was in such pain he couldn't move. He could move his feet although he had a little pain down his legs, so that's a good sign."

The Giants at least have a blueprint for playing without Bonds. They went 25-22 last season when he missed 47 games while recovering from surgery on his left elbow.

The situation is compounded this time around as San Francisco must chase first-place Arizona in the NL West without Bonds and fellow outfielder Ellis Burks, who was placed on the disabled list Saturday with a strained left quadriceps.

"We've just got to stay together and really try to forget who's out and concentrate on who's in there," said Armando Rios, who has three homers in the last two games. "I know it's hard, but we did it last year for a while and we played well. There's no other choice. We've got to do it."

Not only did the Giants lose Bonds, but they lost the game on Brian Hunter's infield single in the eighth after erasing a five-run deficit.

With two outs and the game tied at 9, Giants reliever John Johnstone (2-3) gave up a bunt single to Neifi Perez and a single to pinch-hitter Bubba Carpenter before Hunter hit a soft ground ball in the hole between first and second.

Second baseman Jeff Kent got to the ball but Johnstone dropped the throw as he and Hunter arrived at the base almost simultaneously.

"It was the right call. I tried to squeeze it and it came out," Johnstone said. "I didn't think I had it long enough. If I had held it a second more, he would have been out."

Hunter has been nursing a sore knee.

"Normally I'd get there easily on that type of play," Hunter said. "As soon as I hit it, I knew I had a chance. It was a tough play for those guys."

Gabe White (2-0) retired all four batters he faced in relief and Jose Jimenez got the final out for his fourth save.

The Giants erased a five-run deficit behind seventh-inning home runs by Bonds and Rich Aurilia, but it wasn't enough as San Francisco lost for the fifth time in 19 games.

Todd Helton, the National League RBI leader, went 2-for-3 with a solo homer for Colorado and raised his major league-leading average to .414 (53-for-128). He is hitting .536 (30-for-53) at Coors Field.

Helton's solo homer, his 13th, gave the Rockies a 9-4 lead in the sixth, but Rockies starter Pedro Astacio could not hold on as he missed a chance to set Colorado's career victory record.

Astacio, whose 39 wins with Colorado are tied with Kevin Ritz, gave up seven runs and left the game after Bonds hit his solo homer to cut the lead to 9-7. Stan Belinda issued a walk and gave up Aurilia's fourth homer of the year one out later.

San Francisco starter Shawn Estes, who threw a complete-game shutout against the Rockies seven days ago, gave up seven runs, eight hits and five walks in four innings. He had allowed four earned runs in his previous three starts.

"Everybody was definitely in a somber mood in the clubhouse after the game," Estes said as he talked about Bonds' injury. "That happens and it kind of just takes the wind out of your sails. Hopefully he'll be OK.

Game notes
To replace Burks, San Francisco purchased the contract of Terrell Lowery from Triple-A Fresno. ... Giants 3B Bill Mueller extended his hitting streak to 10 games. ... The Rockies placed OF Larry Walker on the 15-day disabled list. He is expected to miss at least a month with a stress fracture in his right elbow. Colorado purchased Carpenter's contract from Triple-A Colorado Springs and moved RHP Jerry Dipoto to the 60-day disabled list. Carpenter, a career minor leaguer, made his major league debut. ... Helton fouled off nine pitches with two strikes before hitting his 13th homer of the season. He became the sixth player to reach the third deck at Coors Field with his 457-foot homer in the seventh. ... The Rockies scored in double figures for the sixth straight home game.