Meanwhile, the National League Central, which had been just as tight for most of the season, is starting to come into focus a bit. The Pirates rallied to beat the free-falling Brewers, who have now fallen seven games back in the division and 4 1/2 behind Pittsburgh for the second NL Wild Card.
Over the past week, it's become exceedingly likely that the NL Central will be a two-horse race in the season's final week, with the Pirates trying to catch the Cardinals, who also notched a pivotal win Friday night.
IF THE POSTSEASON STARTED TODAY ...
Wild Card: Royals at A's
Division Series: Wild Card at Angels | Tigers at Orioles
Wild Card: Pirates at Giants
Division Series: Wild Card at Nationals | Cardinals at Dodgers
• Postseason picture
Friday's action got started with a matinee at Wrigley Field, which saw the Dodgers plate six runs before ace Clayton Kershaw could even take the hill. Kershaw wasn't at his best, but he did enough to earn his 20th win, despite lasting only five innings.
Instead, it was an unlikely hero who propelled the Dodgers to victory. Catcher A.J. Ellis launched his second and third homers of the year, and the rout was on, as the Dodgers won, 14-5. With the Brewers' loss on Friday night, L.A. clinched a playoff berth.
Shortly thereafter, the NL Central took center stage in Pittsburgh. The Brewers entered the game needing a series victory -- and maybe a sweep -- to put themselves back in the hunt.
For seven innings, everything was going smoothly for Milwaukee. Then Russell Martin happened.
Martin launched a Jonathan Broxton offering into the right-center-field seats for a three-run home run, giving Pittsburgh a 3-2 lead. Before they raised the Jolly Roger, the Pirates had extended that edge to 4-2.
The Bucs' win put all the pressure on St. Louis, and the Cardinals handled it just fine. After getting two first-inning runs, John Lackey pitched 7 2/3 innings of one-run ball, and the bullpen did the rest as the Redbirds maintained their 2 1/2-game lead in the NL Central.
The AL Central offered significantly less drama on Friday night, as the Tigers had already jumped out to a 10-0 lead by the top of the fifth inning. Ian Kinsler's two-run homer in the fifth erased any doubts, and the Tigers cruised to a 1 1/2-game lead.
Things only got worse for the Royals as the night progressed. Both Seattle and Oakland won their games, and the three teams now sit within one game of each other for the final two playoff spots. The Yankees, who have won three straight, and the Indians sit 4 1/2 back.
Finally, the night concluded with a dud from the Giants in a pivotal game in San Diego. After the Giants had cut their NL West deficit to two games mid-week, they're now 3 1/2 back of L.A. and must face Padres ace Andrew Cashner on Saturday.
San Francisco mustered just two hits in seven innings against Odrisamer Despaigne, and three hits total on the night. The Giants enter Saturday desperate for a win, not just to keep their NL West hopes alive, but also to hold off the Pirates for home-field advantage in the Wild Card game.
TODAY'S KEY GAMES TO WATCH (all times ET)
Tigers (Scherzer 16-5, 3.26) at Royals (Shields 14-7, 3.15) 1:05 p.m. Preview
In a battle of established aces, James Shields and the Royals can't afford to lose any more ground on the surging Tigers.
Dodgers (Hernandez 8-11, 4.06) at Cubs (Doubront 4-5, 5.00) 1:05 p.m. Preview
All eyes are on next week's series between the Dodgers and Giants in Los Angeles, and if the Dodgers can continue to pad their lead, they could put themselves in a position to clinch against their rivals.
Phillies (Williams 5-7, 5.03) at A's (Pomeranz 5-4, 2.53) 4:05 p.m. Preview
The A's look to keep their place as the American League's top Wild Card team behind Drew Pomeranz, who makes a spot start while Jason Hammel attends the birth of his second child.
Brewers (Garza 8-8, 3.74) at Pirates (Volquez 12-7, 3.27) 7:05 p.m. Preview
If the Brewers hope to get back in the Wild Card race, they'll have to start by winning Saturday. Standing in their way is Edinson Volquez, who is 4-0 with a 1.73 ERA in his last eight starts.
Mariners (Young 12-8, 3.33) at Astros (Keuchel 11-9, 3.00) 7:10 p.m. Preview
By first pitch in Houston, the Mariners will likely already know the results in Oakland and Kansas City. A Seattle win, coupled with a loss by either the A's or the Royals, would move the Mariners into at least a Wild Card tie.
Reds (Leake 11-12, 3.65) at Cardinals (Wacha 5-6, 3.14) 7:15 p.m. Preview
With the red-hot Pirates hot on their heels, the Cardinals have to keep winning to maintain their Central lead. Michael Wacha, pitching on 10 days' rest after command issues in his first start back, gets the ball against the Reds.
Giants (Petit 5-4, 3.64) at Padres (Cashner 4-7, 2.20) 8:40 p.m. Preview
After dropping Game 1, things don't get any easier for the Giants, who face Cashner at Petco Park -- a tall task. By first pitch, the Giants will know the Dodgers' result, but either way, a win in San Diego is vital.
To calculate a team's magic number, take the number of games it has remaining and add one. Then subtract the difference in the number of losses between that team and its closest pursuer.
AL East: Orioles clinched
AL Central: Tigers nine over Royals
AL West: Angels clinched
AL Wild Card 1: A's 10 over Royals
AL Wild Card 2: Royals 10 over Mariners
NL East: Nationals clinched
NL Central: Cardinals seven over Pirates
NL West: Dodgers six over Giants
NL Wild Card 1: Giants nine over Pirates
NL Wild Card 2: Pirates five over Brewers
A tiebreaker game will be played to determine a division winner, even if the tied clubs are assured of participating in the postseason. If a division championship tiebreaker is necessary, the head-to-head record between the clubs will determine home-field advantage. If the head-to-head record is tied, then division record will be the next tiebreaker.
If two clubs are tied for the two Wild Card berths, home-field advantage will be determined by the head-to-head record between the clubs. If the head-to-head record is tied, then division record will be the next tiebreaker.
• Tiebreaker rules