BOSTON -- Kiké Hernández had spent the better part of this American League Division Series tormenting the Tampa Bay Rays with one huge hit after another.

But when it came time to put the finishing touches on his masterpiece and vault the Red Sox into the AL Championship Series while putting the 100-win Rays down for the count, all Hernández needed was a sacrifice fly.

You didn't think he was going to let the chance go by, did you?

Hernández stayed in the moment and delivered a 300-foot flyball that was plenty deep enough to score speedy pinch-runner Danny Santana, delivering the run that gave the Red Sox an exhilarating and stressful 6-5 victory in clinching Game 4 of the ALDS on a memorable Monday night at Fenway Park.

It was the second walk-off in as many days for these Sox, who turned the tables on the Rays after getting shut out in a 5-0 loss in Game 1.

"You're going to have a chance to win the game, and you can't let this situation get too big," Hernández said, relaying his mindset in that crucial moment. "You're about to win this game, so you need to work on slowing everything down and slowing your breathing down and slowing the game down and starting early and making sure that you see the pitch, and you're not just swinging at your shoes for no reason for trying to be a hero."

The Red Sox will be in action on Friday at 8 p.m. ET in Game 1 of the ALCS on the road in Houston. The Astros advanced by finishing off the White Sox with a 10-1 victory in Game 4 of their ALDS.

There was a fleeting moment when it seemed the Sox might have to board a plane back to St. Petersburg for a winner-take-all Game 5 rather than getting a few days of rest.

However, the pain of Boston surrendering an early 5-0 lead in Game 4 when the Rays came back to tie it in the eighth subsided as soon as Hernández's sac fly left his bat, setting off a mob scene in the middle of the Fenway diamond.

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"There was Kiké, and [Hunter] Renfroe, and then I was under there, just giving body punches," said Red Sox left fielder Alex Verdugo.

Those were victory punches, and it's doubtful Hernández felt a thing.

It was a celebratory night for Hernández and the Red Sox, who punched their ticket as one of the final four teams that will play baseball in 2021.

"I mean, here we are surprising everybody but ourselves," said Hernández. "We knew in Spring Training we had the team to make it this far, and here we are."

There are a lot of reasons the Red Sox -- picked by nearly every prognosticator to finish fourth in the AL East -- are where they are, and Hernández is prominent among them.

All he did in this ALDS was go 9-for-20 (.450 average) with four runs, three doubles, two homers, six RBIs, 18 total bases and an eye-popping 1.329 OPS. Talk about having a monster series.

"We felt very comfortable with him [in the ninth inning]," said Red Sox manager Alex Cora. "He was putting good at-bats after good at-bats, and he did an amazing job against a tough pitching staff, and we're very proud of him."

After all, this is why Hernández, a World Series-winning member of the Dodgers last season, came to Boston in the first place. The free agent wanted to stay on a winning stage, but he wanted to play a more important role.

"I wanted to play every day where it mattered," said Hernández. "I told my mom, 'There's nothing that compares to winning the World Series, but I want to go somewhere where I can win the World Series and be in that starting lineup every day.' It feels like I'm a little bit more important piece than just one more guy on that team. Boston ended up being the greatest of fits. I don't regret that decision one bit."

The overachieving Red Sox are a team full of stories like Hernández, who signed a modest two-year, $14 million deal and played the best baseball of his career.

Perhaps the best story of all is Garrett Whitlock, the Rule 5 Draft pick the Red Sox pried from the Yankees back in December who turned into the team's best reliever.

After Ryan Brasier gave up three straight hits in the eighth inning of Game 4 to tie the game, out of the 'pen came Whitlock, who inherited a runner on second with nobody out. The power righty mowed through Tampa Bay's 2-3-4 combination of Wander Franco, Brandon Lowe and Nelson Cruz, putting some momentum back on Boston's side.

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And in the ninth, Whitlock again came through with a 1-2-3 frame, putting the offense in position to win the game simply by scoring a run.

"People still call him the secret weapon," said Hernández. "It's no secret anymore. Garrett Whitlock is legit. That is an electric arm with three-plus pitches at his age, with his experience coming into this year. It's not every day that a Rule 5 Draft pick gets to close out a Wild Card Game and then win a game that wins a playoff series. You don't see that every day."

You don't see stories like these Red Sox every day, who are guided by Cora, who is now 5-0 in series clinching games and 15-4 overall in the postseason.

Only Cora's former skipper, Terry Francona, has won more consecutive clinching games to start a managerial career than Cora.

"Not too many people gave us a chance from the get-go, but we believed," said Cora. "We always said we had a good baseball team that had some holes, and we still have some holes, but at the end, for how bad it looked sometimes, we're still here. We're still in the dance. We're still in the tournament, and we're moving on to the ALCS."