ST. LOUIS —Jonny Gomes began Sunday out of Boston Red Sox lineup.

But Shane Victorino’s back tightened up again and Boston manager John Farrell made his best substitution of the World Series.

With Gomes inserted in the lineup and batting fifth, he unloaded on a Seth Maness fastball, clocking a three-run home run in the sixth inning, to lead the Red Sox to 4-2 victory in Game 4 of the Series.

“The one thing I always wanted was the opportunity,” Gomes said. “I got the opportunity tonight. One thing I can guarantee is that when I’m in the lineup I’m going to be swinging.”

During batting practice, Farrell said “it became obvious (Victornio) couldn’t go.

“You know what, it turns out his replacement is the difference in this game … (Gomes) is ready every day.”

David Ortiz also shined, reaching base four times on three hits and a walk. He scored twice.

Boston’s victory not only evened the Series 2-2, it assured that there will be at least one more game at Fenway Park.

After Monday’s Game 5, the Series will resume in Boston on Wednesday.

On Sunday, the Red Sox pieced together their pitching with starter Clay Buchholz going four innings and Felix Doubront pitching 2 2/3 innings. Junichi Tazawa, John Lackey and Koji Uehara were also strong out of the pen. (And, yes, Lackey is still starting Game 6).

Uehara allowed one single in the ninth. But with two outs, and clutch hitter Carlos Beltran up, Uehara picked off pinch-runner Kolten Wong.

Buchholz did not figure to last a long time because of his weakened arm, but he did give the Red Sox four innings, allowing three hits and one unearned run.

Buchholz, his fastball rarely reaching 90, used a variety of curveballs and change-ups to keep the Cardinals off balance.

“He gave us everything he couldn’t” Farrell said.

Matt Carpenter singled off Buchholz in the fifth and reach second when center fielder Jacoby Ellsbury could not come up with the ball cleanly. It was a costly error as Beltran singled in Carpenter.

St. Louis starter Lance Lynn, meanwhile, was cruising. He faced only 12 batters in four innings (Ortiz singled, but Gomes grounded into a double play).

Boston then tied the game in the fifth inning. Ortiz led off with a double to right center. Standing on second base, Ortiz gestured to the Boston dugout, trying to ignite a little fire in his teammates.

Gomes followed and quickly fell behind 0-2. But Gomes fouled off pitches, worked a full count and walked on pitch No. 10.

Lynn then walked Xander Bogaerts to load the bases with no outs. The slumping Stephen Drew came to bat.

Drew lofted a fly ball to left field, deep enough to score Ortiz. Matt Holliday’s throw home bounced into the sliding Ortiz.

In the dugout, Ortiz gathered his teammates around him “for a timely conversation,” according to Farrell.

David Ross struck out. Mike Carp pinch-hit for Buchholz and grounded out.

Doubront entered for Buchholz and retired the first eight batters he faced.

In the sixth, Pedroia began a two-out rally with a single. Lynn pitched carefully to Ortiz, walking him.

Cardinals manager Mike Matheny called on Maness, a sinkerball pitcher, to face Gomes. Maness threw a sinker that did not sink much. Gomes got all of it. He dropped his bat, pumped his fist in the air, and Boston enjoyed a 4-1 lead.

“Seth has been able to help us out all year long to get the big out,” Matheny said. “It just didn’t work tonight.”

Doubront was dominating until Shane Robinson hit a pinch-hit double with two outs in the seventh,

Craig Breslow, who has not had a good Series, relieved and gave up a RBI single by Carpenter, closing St. Louis to 4-2. Breslow then walked Beltran on four pitches and exited. Tazawa ran in to face the slugger Holliday.

Holliday, representing the go-ahead run, grounded out to Pedroia.

Lackey, on a day he was scheduled to throw a bullpen session, came in the eighth for an inning of relief.

Bogaerts, the third baseman, charged a grounder and made a solid throw for the first out.

Bogaerts then dove and snagged a hard grounder down the line by Molina. But Bogaerts’ throw was wild and Molina reached second.

Molina reached third on a wild pitch, but Lackey escaped, getting Jon Jay to pop out, and David Freese to ground out.

Uehara entered in the ninth to close it out. He got Daniel Descalso to ground out. Pinch hitter Allen Craig singled. But Uehara retired Carpenter and then picked off Wong..