SAN FRANCISCO – The Giants sure are tough to eliminate this postseason.

Barry Zito and Co. gave themselves at least one more game in the NL Championship Series with a 5-0 victory Friday in St. Louis that forced Sunday’s Game 6 back at AT&T Park.

Just where the NL West winners want to be with their season on the line.

“It’s great to be back in San Francisco. There is no tomorrow,” Giants right fielder Hunter Pence said. “It’s a unique feeling. It has brought the best out of us.”

The wild-card Cardinals know how hard winning the last one can be considering what this Giants team already did during these playoffs: winning three straight on the road at Cincinnati in the division series after falling behind 2-0.

Game 2 winner Ryan Vogelsong starts for the Giants for the second time this series against Chris Carpenter, who lost that matchup at AT&T Park last Monday.

The Giants have to like their chances to push the series to a decisive Game 7 with Vogelsong on the mound. He went seven strong innings in a 7-1 Game 2 victory.

Giants General Manager Brian Sabean said he wasn’t surprised to see his team on the field Saturday for an optional practice — realizing they didn’t want to lose any momentum from the night before.

“Sometimes you wonder how much at this stage that there is a home-field advantage,” Sabean said. “In some cases, because of the bullpens, it’s probably as much as whoever gets the lead and can hold off the other ballclub from scoring will win the ballgame.”

St. Louis postseason ace Carpenter sure is looking forward to another chance, too.

He has been plenty reliable this time of year for the Cardinals, with his 10 victories the most in franchise history. His stuff never felt right the last time out against the Giants, when he allowed two earned runs, five in all, and six hits in four innings.

He is counting on commanding his fastball better this time out.

“The last time out my stuff went backwards a little bit,” Carpenter said. “I was trying everything I could to get outs but unfortunately it didn’t work.”

YANKEES: CC Sabathia will have his pitching elbow examined following inflammation that landed him on the disabled list in August.

MARLINS: Closer Heath Bell, dangled as trade bait before the July 31 non-waiver deadline, was sent to the Diamondbacks, along with cash, in a three-way deal that brought the Marlins minor league infielder Yordy Cabrera from Oakland. The deal also had Diamondbacks outfielder Chris Young going to the A’s in return for infielder Cliff Pennington.