BOSTON -- In upending the rival Yankees in a four-game American League Division Series win, the Red Sox proved that their 108-win regular season was no fluke. But now an even bigger test awaits in the defending World Series champion Astros, who took down Boston in a four-game ALDS last year.
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The Red Sox rode their big arms and bats against the Yankees and even developed some confidence in their oft-maligned bullpen. Manager Alex Cora pushed all the right buttons in an impressive postseason debut.
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This time, the Sox will have to win four games in the AL Championship Series to advance, and it won't be easy against a Houston team that had the second-best record in the Majors at 103-59 and swept a talented Indians team in the ALDS.
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Here are five things we learned about the Red Sox as a result of their ALDS victory:
1. Sale is healthy
There was a lot of worry in Red Sox Nation heading into the ALDS about Chris Sale, and rightfully so. The lanky lefty ace had logged just 17 innings from July 28 through the start of the playoffs due to multiple bouts of left shoulder inflammation, and his fastball was in the low 90s in his final start of the regular season. But Sale quelled all those fears from the first pitch of Game 1, when he fired a 95.4-mph heater for a strike. Sale gave everyone even more confidence when Cora went to him in the bullpen for a crucial eighth inning in the Game 4 series clincher, and he dazzled, mowing down the Yankees on just 13 pitches. Sale is lined up for Game 1 against the Astros in a marquee matchup against Justin Verlander.
2. Bullpen starting to settle in
Confidence in Boston's inconsistent bullpen reached an all-time low in Game 1 of the ALDS, when Sale left with a 5-0 lead after 5 1/3 innings and the Yankees whittled it to 5-4 by the ninth inning. But as the series evolved, the relievers gained confidence and settled into roles. Matt Barnes and Ryan Brasier distinguished themselves as the two setup men Cora will go with in high-leverage moments. Despite his near meltdown in Game 4 of the ALDS, Craig Kimbrel ultimately earned the save, and he will be leaned on heavily in the ALCS.
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3. Holt should -- and likely will -- play against righties
Somewhat surprisingly, Brock Holt didn't get on the field in the first two games of the ALDS, even though he was one of Boston's hottest hitters down the stretch. Once he got a chance to play in Game 3, Holt became the first player in the history of postseason play to hit for the cycle. That performance could earn him starts against righties in the ALCS. Dallas Keuchel is the only lefty in Houston's rotation, so Holt could start games against Verlander, Gerrit Cole and Charlie Morton. In his last 52 plate appearances, Holt has a slash line of .447/.500/.894 with five homers and 17 RBIs. Cora has the option of starting him at first base, second base or third base.

4. Price still has postseason issues to conquer
Lefty David Price seemed more confident and determined than ever that he would at last vanquish his postseason demons as a starter when he stepped to the mound in Game 2 of the ALDS. Instead, disaster struck. Price gave up two early blasts to Aaron Judge and Gary Sanchez and lasted just 1 2/3 innings. Perhaps not having to deal with the circus that comes with playing the Yankees will help Price this time around. Cora has already committed to him for Game 2 on Sunday night. For Price to be at his best, he needs to do a much better job of mixing the speed of his pitches to keep hitters off-balance. Everything blended together in Game 2.

5. Cora will use his bench early and often
Mookie Betts, Andrew Benintendi, J.D. Martinez, Xander Bogaerts and Jackie Bradley Jr. will play just about every inning in the ALCS. But the other four lineup spots (catcher, first base, second base, third base) are completely fluid. Cora used four different lineups in the four games of the ALDS, and he'll continue to mix it up. Christian Vazquez gave the Sox some competitive at-bats when he was thrust into action for Games 3 and 4, so the heavily slumping Sandy Leon could become the backup in this series. First base depends largely on the health of Mitch Moreland, who hasn't played since sustaining a right hamstring injury in Game 2. Steve Pearce held down the fort nicely on offense and defense. Rafael Devers and Eduardo Nunez could become a classic, lefty-righty platoon at third base. Keep an eye on second base, where Ian Kinsler is the team's best defender, but Holt also could see action there.