MILWAUKEE -- Does Josh Hader throw 100 mph now?

That’s what the scoreboard said on Opening Day.

“That's going to be a problem for hitters if that keeps happening consistently,” said Brewers third baseman Travis Shaw.

Shaw was one of the other heroes of the Milwaukee’s come-from-behind 6-5 walk-off win over the Twins in 10 innings on Thursday at American Family Field, hitting a game-tying two-run double with two outs in the bottom of the ninth inning to force extras and bring Hader to the mound in the 10th. Hader had forgotten that the automatic runner on second base rule had returned for 2021, but it didn’t appear that realization rattled him when he started firing fastballs.

• Fans fuel Brewers' rally in opener: 'You felt it'

In Hader's 172 regular-season appearances before Thursday, Statcast counted that he threw 3,648 pitches. Of those, 2,832 (77.6 percent) registered as four-seam fastballs. It had gone pretty well, one might say; Hader was the National League Reliever of the Year in 2018 and ’19, and his 44.1 percent career strikeout rate entering this season was best in Major League history for a pitcher who had logged more than 35 innings.

And yet, none of those fastballs from 2017-20 topped the 99.2 mph four-seamer that Hader threw at the Cubs’ Willson Contreras on Oct. 1, 2018, at Wrigley Field. That was the NL Central tiebreaker game, in which Hader closed the door on a 3-1 Brewers victory and the third division crown in franchise history. He threw the three hardest pitches of his career that day, all in that at-bat against Contreras. The other two were 98.8 mph.

In 2019, Hader topped out at 98.6 mph on July 20 against the D-backs. In '20, his hardest fastball was 96.8 mph on Sept. 14 against the Cardinals, and his average four-seamer was 94.5 mph, but he posted another solid season thanks to higher usage of his slider. This spring, Hader spoke of continuing that trend of less reliance on the fastball, and he even talked once again about throwing more changeups.

Then he took the mound Thursday in front of fans and started throwing gas at the Twins.

Ten of Hader's 11 pitches were fastballs; the other was a slider. He struck out Willians Astudillo on three straight fastballs. He struck out Luis Arraez on four pitches, three of them fastballs and the other a slider in the dirt that allowed the Twins’ automatic runner to reach third base. Hader kept the runner there by striking out Jake Cave on four pitches, all fastballs. The Brewers won the game in the bottom of the inning.

“He’s as good as it gets,” Twins manager Rocco Baldelli said. “The fact you know essentially what he’s going to do and everyone in the league is able to send good hitters up to face him and he still finds a way to miss those bats -- it’s a combination of a lot of things, but he’s pretty special at what he does.”

The last pitch to Arraez is the one that registered 100 mph on the stadium scoreboard.

Statcast had it at 99.6 mph, making it the hardest pitch Hader has thrown in the big leagues, in the regular season or the postseason. Round up for the scoreboard reading, and you’ve got your 100 mph pitch.

“I think one of the biggest things, like I said earlier in Spring Training, was working on my strength and being able to use my body efficiently down the mound,” Hader said. “Getting on a good throwing program and making the [scapular muscles] and the [rotator] cuff stronger as well, I think that's played a big part in it.

“I haven't really paid much attention to the radar gun. I know in spring occasionally I was throwing 95, but when you get these fans and especially at AmFam [American Family Field], man, we get loud. I think that's a big adrenaline push for us. I'm excited to have fans back, and the way we're playing, making that comeback, that was huge. I mean, it's hard not to get a big adrenaline rush.”

Brewers manager Craig Counsell surmised before Thursday’s game that Hader should be fresh after throwing only 19 innings in the shortened 2020 regular season. “And I was right,” he joked afterward.

“He was electric today,” Counsell said. “He struck out the side obviously, but two of the guys do not strike out. Arraez and Astudillo are incredibly hard guys to strike out -- and that tells you a lot.”

Brewers starter Brandon Woodruff used the same word: Electric.

"I think this is the most electric Josh Hader I think I've ever seen, including playoffs,” Woodruff said. “He was throwing some BBs in there; they were missiles. And the thing was, he was putting them right on the edge of the top of the zone, where, you know, they can very easily be called a strike if you can't lay off them. When he's doing that, and he's throwing the ball like that, you have zero chance.”