ST. LOUIS — When the Boston Red Sox traded defensive wizard Jose Iglesias to get pitcher Jake Peavy, they figured they needed one more reliable starting pitcher.

And Boston needs him Saturday night, more than ever.

Peavy will start Game 3 of the World Series against the St. Louis Cardinals. The teams split the first two games in Boston and now move to Busch Stadium for three games.

Peavy, 32, has the resume, with a Cy Young Award and three All-Star appearances, but has never pitched in a World Series.

“This is what I’ve lived for my whole life, my whole baseball career,” Peavy said, “to have this opportunity to go out there on the biggest stage and have a chance to help your team win a World Series game, and a World Series title.”

Peavy is an excitable guy. But while he’s energized and has had success in previous years, he’s no guarantee. Peavy was 4-1 with a 4.04 ERA after he came to the Red Sox on July 31.

In the American League division series, he allowed only one run over 52/3 innings against Tampa Bay.

But in Game 4 of the ALCS, Peavy lasted only three innings (five hits, seven runs, three walks). Not surprisingly, Peavy is still talking confidently.

“Everything is fixable,” Peavy said. “It wasn’t too much to read into it, really. Just a small adjustment that can make all the difference in the world.”

Peavy’s start Saturday becomes magnified because he’s now Boston’s No. 3 starter. Clay Buchholz is fading with a tired arm.

Manager John Farrell said Buchholz will start Sunday.

One reason the Red Sox traded for Peavy was because Buchholz was on the disabled list. Now with Buchholz again not 100 percent, Boston is relying even more on Peavy.

St. Louis will start Joe Kelly (10-5, 2.69), who appeared in 37 games, becoming a starter in late July. In the playoffs he’s 0-1 in three starts, allowing eight earned runs over 161/3 innings.

DAVID ORTIZ will play first base and Mike Napoli will sit this weekend because the games will be played by National League rules – no designated hitter – for the next three games.

Ortiz said playing in the field won’t be much different than what he normally does.

“When I play first base, I try to communicate with (second baseman Dustin) Pedroia and try not to get in his way,” he said. 

DANIEL NAVA will get his first start in the World Series. Farrell said Nava will play left field while Jonny Gomes goes to the bench.

“I’ve tried to stay in the game mentally and keep the routine the same,” Nava said.

Nava has come in as a pinch hitter in each of the first two games. He doubled in Game 1, then faced hard-throwing closer Trevor Rosenthal in Game 2, striking out.

“He hits his spots at 99 mph,” Nava said. “That makes it a challenge. “We know they’ve got good pitchers. We know they throw hard. And it’s cold. It’s not a fun combination.” 

SHORTSTOP STEPHEN Drew is batting .095 in the playoffs but look for him in the lineup.

“While he’s had struggles, we live with him,” Farrell said. Drew’s defense “has been critical. (Thursday) night there’s probably three or four plays that he makes that might otherwise build into a potential inning for the Cardinals.” 

GOLD GLOVE finalists were named for each position in each league. Pedroia, center field Jacoby Ellsbury and right fielder Shane Victorino were the nominees from Boston.

Kevin Thomas can be reached at 791-6411 or:

kthomas@pressherald.com

Twitter: @ClearTheBases