Once again, the San Francisco Giants have their backs up against the wall in the postseason.

Saturday night at Wrigley Field the Chicago Cubs took a commanding two games to none lead in the best-of-five National League Division Series with a 5-2 win over the Giants (box score). Starters Kyle Hendricks (injury) and Jeff Samardzija (ineffectiveness) both exited the game early, and Chicago won the battle of the bullpens.

Game 3 of the NLDS will be played Monday at AT&T Park in San Francisco. Here are nine things to know about Game 2.

1. Baez made an incredible baserunning play

Cubs tenth man Javier Baez won Game 1 with an eighth inning home run Friday, and on Saturday, he scored Chicago's third run thanks to a fantastic baserunning play. He was on second when Hendricks blooped a single to center, and because Baez read it so well, he took off and scored even though the ball didn't fall too far beyond the infield. Here's video. Very aggressive and heads up baserunning created a run.

2. Hendricks left with an injury

Hendricks, the MLB ERA leader in 2016, was forced to leave Game 2 after 3 2/3 innings because he took an Angel Pagan line drive to his right forearm. The ball left Pagan's bat at 94 mph, per Statcast. Hendricks threw several test pitches, but according to the MLB Network broadcast, his forearm started to tighten up and the Cubs removed him as a precaution.

The club officially called the injury a right forearm contusion and said x-rays came back negative The Cubs are already planning to use four starters in the NLDS -- Jake Arrieta and John Lackey are scheduled to start Games 3 and 4, respectively -- which means Hendricks isn't scheduled to start anytime soon. He'll have a few days to rest up for a potential NLCS Game 1 start, should the Cubbies advance.

3. A pitcher went deep!

After replacing Hendricks, lefty Travis Wood came out of the bullpen and not only threw 1 1/3 scoreless innings, he also hit a home run. He hammered George Kontos' get-me-over fastball in the fourth inning. Check it out:

Wood is the first Cubs pitcher to homer in the postseason since another Wood: Kerry did it in Game 7 of the 2003 NLCS. Rick Sutcliffe is the only other Cubs pitcher to homer in the playoffs. Pretty crazy. The fans wanted a curtain call, and Wood delivered:

Wood is also only the second reliever to homer in a postseason game, joining Rosy Ryan. Ryan went deep for the New York Giants against Allen Russell of the Washington Senators in Game 3 of the 1924 World Series.

The last pitcher to hit a home run in the postseason in general was Joe Blanton. He did the honors against then-Rays righty Edwin Jackson in Game 4 of the 2008 World Series.

4. A pitcher pinch-hit!

Because Jeff Samarzija lasted only two innings, Giants manager Bruce Bochy was stuck using a series of relievers and pinch-hitter for most of the game. Rather than burn a top pinch-hitter with one out and bases empty in the fifth, Bochy used his ace, Madison Bumgarner.

Bumgarner hit into what should have been a 5-3 ground out, but Kris Bryant made two errors on the play -- he booted the grounder then threw the ball away -- allowing MadBum to reach second. He's a good hitting pitcher, though that still equaled a .186/.268/.360 batting line in 2016. Good is a relative term here.

5. Chicago's lefty relievers came up big

Prior to the NLDS, R.J. Anderson wrote the Cubs match up well with the lefty heavy Giants thanks to their three left-handed relievers: Aroldis Chapman, Mike Montgomery, and Wood. Sure enough, Wood and Montgomery combined to retire eight of the 10 batters they faced after Hendricks had to leave the game. One of the baserunners was Bryant's double-error on Bumgarner. Chapman then retired the side in the ninth.

6. Samardzija failed to beat his former team

Saturday night, Samardzija had a chance to become the first pitcher to beat his former team in the postseason in a decade. It did not go well. He allowed four runs on six hits and a walk in two innings.

The Cubs scored their fourth run before making their fifth out, and it was all downhill from there. Samardzija and the Giants hope he'll get a chance to face the Cubs again later in the series. If he does, it'll be in a decisive Game 5.

7. Pagan reached on catcher's interference, again

In the bottom of the first, Pagan became the first player to reach base on a catcher's interference call in the postseason since then-Cardinals outfielder Jon Jay in Game 4 of the 2013 NLCS. It was also Pagan's fourth catcher's interference call in 2016. It's been a long time since the Giants had that many.

Yankees outfielder Jacoby Ellsbury led all players with 12 (!) catcher's inteference calls this season. That's easily the all-time single-season record. Pagan is a distant second with his four.

8. The Cubs are almost unbeatable with a four-run lead

The Cubs jumped out to a 4-0 lead in the second inning, and while we know no game is truly over until it's over, Chicago had to feel pretty good. They've been damn near unbeatable this season when taking a four-run lead.

It blows my mind the Cubs held a four-run lead in 72 (!) of 162 games during the regular season. That's more than 40 percent of their games (44.4 percent, to be exact). Good gravy.

9. The Giants have their backs up against the wall, again

The NLDS now shifts to AT&T Park in San Francisco with the Giants facing elimination. They've been through this before. The Giants have won nine straight elimination games dating back to the 2012 NLDS. They've already won one elimination game this postseason: the Wild Card Game against the Mets.

Of course, the Giants did not face a team as good as these Cubs in any of those nine elimination games. I say that with all due respect to the 2012 Reds, 2012 Cardinals, 2014 Royals, and 2016 Mets. If San Francisco is going to climb out of this hole -- or even just force a Game 4 -- they're going to really have to earn it. They're in some serious jeopardy.