ST. LOUIS (AP) -- There's no telling how these wacky World Series games will end.
One night after a rare obstruction call, Jonny Gomes hit a decisive homer when he wasn't even in the original lineup and Koji Uehara picked off a rookie at first base for the final out.
An entertaining, even goofy World Series is tied at two games apiece following Boston's 4-2 victory Sunday night, which ensured the title will be decided back at Boston's Fenway Park.
"Emotional roller-coaster here, obviously," Gomes said.
Inserted into the lineup about 75 minutes before gametime, Gomes hit a tiebreaking, three-run shot off reliever Seth Maness in the sixth inning.
Felix Doubront and surprise reliever John Lackey, both starters during the regular season, picked up for a gritty Clay Buchholz to help the Red Sox hang on.
And of course, another bizarre ending: Uehara picked off pinch-runner Kolten Wong -- with postseason star Carlos Beltran standing at the plate.
It was the first postseason game in history to end on a pickoff, according to STATS.
Game 5 is Monday night at Busch Stadium, with Boston left-hander Jon Lester facing Cardinals ace Adam Wainwright in a rematch of the opener won 8-1 by the Red Sox.
Gomes helped get Boston started in the fifth when he followed David Ortiz's leadoff double with a 10-pitch walk that tired starter Lance Lynn, who had faced the minimum 12 batters through the first four innings.
Stephen Drew's sacrifice fly tied the score 1-all, erasing a deficit created when center fielder Jacoby Ellsbury's third-inning error advanced Matt Carpenter into scoring position for Beltran's RBI single.
Ortiz, who homered in the first two games of the Series, had three of Boston's six hits and was the club's leader, smacking his hands together and screaming at teammates to get going when he pulled into second base on his double. Then, after the fifth inning, he huddled the Red Sox for a pep talk in the dugout.
Not long after, Gomes' drive put Boston ahead 4-1 in the sixth.
With adrenaline taking over, Gomes spiked an arm through the air as he rounded first base, yelled and banged his chest with a fist twice. Teammates tugged on Gomes' beard for good luck when he got back to the dugout, including a two-handed pull by Mike Napoli.
While talk of umpires' calls dominated discussion following two of the opening three games, this one turned on a manager's pregame decision.
John Farrell's original Red Sox lineup didn't include Gomes, but Victorino's back had been bothering him since Saturday, so Daniel Nava was moved from left field to right and from fifth to second in the batting order. Gomes was inserted into the No. 5 hole behind Ortiz.
"Since I signed up for this game, all I wanted was the opportunity," Gomes said. "I just wanted to be in the box."
Gomes had been 0 for 9 in the Series before the home run, and Red Sox outfielders had been 4 for 40 with no RBI. Following Dustin Pedroia's two-out single and a four-pitch walk to Ortiz by Lynn, Maness threw five straight sliders to Gomes, who sent the last one into the Red Sox bullpen in left as Matt Holliday kept running back only to run out of room.
"I take a lot of pride in the at-bat in front of me and behind me," Gomes said. "Obviously, Big Papi is pretty much an intentional walk. I did what I could to give him a little protection."
Carpenter singled in a run in the seventh off Craig Breslow in the seventh after pinch-hitter Shane Robinson doubled with two outs against Doubront on a ball that skidded away from Gomes. Junichi Tazawa came in and got Holliday to hit an inning-ending grounder to second, a night after allowing a tiebreaking, two-run double to Holliday.
Doubront got the win with 2 2/3 innings of one-hit relief. Lackey, the Game 2 loser and Boston's probable Game 6 starter, pitched the eighth for his first relief appearance in nine years, overcoming a two-base throwing error by third baseman Xander Bogaerts -- Boston's seventh error of the Series -- and a wild pitch.
With a runner on third, Lackey got Jon Jay to pop up and David Freese to ground out.
Uehara, Boston's sixth pitcher, got three outs for his sixth save this postseason, completing a six-hitter.
Lynn was the hard-luck loser, leaving with the score tied and two on for Maness, who allowed Gomes' homer on his fifth pitch.
A night after one of the craziest endings in Series history -- an obstruction call on Red Sox third baseman Will Middlebrooks -- Boston ensured the Series will return to Fenway Park for Game 6 on Wednesday night.
"We stayed away from throwing the ball down the third base line tonight," Gomes said.
It was a special anniversary for both teams. Exactly nine years earlier, the Red Sox completed a four-game sweep of the Cardinals across the street at old Busch Stadium for their first championship since 1918. And two years earlier, Freese hit a tying, two-run, two-out triple in the ninth against Texas and a winning homer in the 11th to force a Game 7, which St. Louis won the following night.
Buchholz, in his first appearance since the AL championship series finale on Oct. 19, fought through shoulder issues and his velocity topped out at 90 mph. He lasted a season-low four innings and 66 pitches before he was lifted for a pinch-hitter, but he allowed just an unearned run and three hits.
"We have guys with heart. Clay, he brought everything he's got," Ortiz said. "I have never seen Clay throwing an 88 mph fastball."
Fielding for the Red Sox became trouble again in the third when Carpenter singled to center with one out, and the ball appeared to take a high hop and roll away from Ellsbury. Carpenter sprinted to second on the second error of the Series by Ellsbury -- who had just three during the regular season.
Beltran singled into center field two pitches later, making him 8 for 10 with 12 RBIs with runners in scoring position during the postseason.
There almost was another miscue in the fourth following a one-out walk to Jay. Freese bounced to Drew, and the shortstop grabbed the grounder on the run and flipped the ball with his glove high to Pedroia at second. He jumped and just got his left foot down in time to force Jay, who slid into him hard.
After Ortiz's double to the right-center field wall in the fifth, Gomes fell behind 0-2 in the count and then worked out his walk. Lynn appeared to be too fine with his pitches as he walked rookie Bogaerts, loading the bases, and Drew lofted a fly to medium left near the foul line.
Holliday's one-hop throw home hit the sliding Ortiz in the back and bounced away. Lynn recovered to strike out David Ross and induce an inning-ending groundout from pinch-hitter Mike Carp.