In the bottom of the first, Betts stole two bases at once.
With plenty still left in the tank, Betts clubbed a three-run homer over the Green Monster to give the Red Sox a 4-0 lead in the second. There was no doubt who the tone-setter was in a 9-4 win that boosted Boston to 5-2 on the season.
"Mookie's a great player," said Harper. "I think being able to go from second base to center field is pretty impressive. He's got ups. It's pretty impressive to see him jumping over the wall like that and robbing a homer. Of course, I want it to be 2-0 in the first inning like that. Sometimes great players make plays."
It was quite a wide-ranging display of skills from the electrifying center fielder.
"It's the Mookie Show," said Red Sox left fielder Hanley Ramirez. "He's bringing a lot of energy to our club every day."
For the record, the fuel behind that energy, according to Betts, was an omelet and two pancakes. Perhaps Betts will turn that meal into a superstition.
"I may need to," said Betts. "That's pretty easy to make."
If not for Betts, the Red Sox and starter Rick Porcello would have been in a quick 2-0 hole. But Betts raced back to the wall in right-center field and perfectly timed his jump to snare the drive by Harper before it could land in the Red Sox's bullpen.
"That was a game-changer right off the bat," said Porcello. "The first inning, I could've given them two runs. That was still early. The way he played today was wonderful to watch."
The crowd at Fenway Park, which had already seen a riveting pregame ceremony just minutes earlier, erupted with approval when Betts came up with the catch.
"I just know I told [Shane Victorino] at one point I'm trying to catch it and he kind of let me go," Betts said. "As far as jumping and catching it, it just kind of happened in a blur."
It didn't take long for Betts to create more excitement in the bottom of the inning.
Betts led off with a walk. With one out and David Ortiz at the plate, Betts went for the steal of second. As he slid in safely, Betts was alert to the fact the Nationals didn't have anybody covering third due to the shift on Ortiz.
So literally as Danny Espinosa finished applying the tag at second, Betts broke away and sprinted to third. In fact, it was hard to tell if Betts might have been off the bag and already en route to third with Espinosa's glove still on his back.
Betts narrowly beat the tag by pitcher Jordan Zimmermann, who hustled over to try to get the out at third.
"That was fun," said Ortiz. "That was maybe the craziest thing I've ever seen in baseball. We were talking about it and I was explaining to him what he did because I don't think he knows. I know he doesn't know, because when I was telling him what he did, he was like, 'Really?'
"I'm like, 'Bro, not even if you practice it can you do that.' I asked him what he was thinking and he was like, 'I know they play you with a shift and I got up right away and I know they weren't going to catch me,' because he said he saw where the pitcher was and that was the reason why he started moving towards third.
"I told him, 'Hey, it was a second after the shortstop tagged you that you got up and went, like the shortstop was breathing on you.' It was unbelievable. That kid is an unbelievable athlete and he's going to be a superstar. I keep on saying that."
Betts scored on Ortiz's single to left for the first run of the game. And an inning later, Betts hit a laser into the third row of the Monster Seats.
"The first two or three innings, Mookie took the game over single-handedly, it seemed like," said Red Sox manager John Farrell.