Athletics vs. Royals, 2014 A.L. Wild Card Game final score: Kansas City wins, 9-8, on walk-off single

Salvador Perez hit a walk-off single in the 12th inning to cap an improbable comeback in the Royals' 9-8 victory over the Athletics in the AL Wild Card play-in game on Tuesday in Kansas City.

Perez lined a 2-2 slider from A's reliever Jason Hammel down the left field line to score Christian Colon, who stole second base earlier in the at-bat -- the Royals' seventh steal of the game -- after reaching on an infield single that plated the tying run. The exhilarating moment for Perez washed away the memories of his two previous plate appearances, both of which ended in outs with the winning run on base.

Kansas City entered the inning trailing, 8-7, after A's infielder Alberto Callaspo hit a go-ahead single in the top half of the frame. With one out, Eric Hosmer tripled off the left-center field wall, starting the Royals' latest of several rallies.

The game-winning hit by Perez rendered a monstrous performance from Brandon Moss, who homered twice and drove in five runs, useless.

Moss opened the scoring in the top of the first inning with a two-run shot off of James Shields, but the Royals bounced back with a run against A's starter Jon Lester in the bottom of the frame and added two more in the third to take a 3-2 lead. Shields settled down after the eventful opening inning, which included the Royals' rally ending on a baserunning gaffe by Billy Butler. Kansas City's ace kept Oakland off the board through the fifth inning, but ran into trouble to open the sixth before being replaced by Yordano Ventura.

Three pitches into his second-career relief outing, the 23-year-old Ventura served up a three-run homer to Moss on a 98-mph fastball, turning a one-run lead into a two-run deficit. Moss became the ninth Athletics player to hit two or more home runs in a postseason game, joining the likes of Reggie Jackson, Rickey Handerson and Frank Thomas.

The A's added two more in the sixth on singles from Derek Norris and Coco Crisp, further twisting the knife into the hearts of an energetic, sold-out crowd at Kauffman Stadium.

The boisterous Royals fans weren't kept quiet for long.

The Royals used an aggressive approach on the bases in the eighth inning to first chase Lester with one out after an error, a run-scoring single by Lorenzo Cain and a walk, then plate two more against A's reliever Luke Gregerson. Kansas City at that point was within a run with still only one out in the inning, but with two runners on base Gregerson struck out Salvador Perez and Omar Infante to escape with the lead intact. An inning later, Sean Doolittle was unable to do the same.

Josh Willingham opened the ninth with a bloop single to right field, putting the tying run on base. Jarrod Dyson was tabbed to pinch-run for Willingham, and he advanced to second on a sacrifice bunt before a gutsy stolen base got him to third. Dyson scored on a sacrifice fly off the bat of Nori Aoki, forcing extra innings.

While 2014 first-round draft pick Brandon Finnegan kept Oakland off the board in the top half 10th and 11th innings, the Royals got the leadoff hitter on base in the bottom of each frame. Nothing came of either advantageous situations, and it looked as if Kansas City would have to wait at least another year for a playoff series. That is, until Hosmer, Colon and Perez came through not long before midnight CT.

Lester allowed six runs -- five earned -- on eight hits in 7⅓ innings. Oakland's prized midseason acquisition struck out five batters and walked two.

Shields was charged with four earned runs in his five innings of work. He left the game after throwing just 88 pitches, the lowest single-game total for Shields during his two-year tenure with the Royals, notes Tyler Kepner of the New York Times.

The Royals move on to face the Angels in the AL Division Series beginning on Thursday in Anaheim.