Despite having Australia 122 for 8 in their first innings, England fell to a 251-run loss in Birmingham, with a final-innings capitulation that might have been expected to bring about wholesale changes.
But they are likely to make only two changes at Lord's, one of them injury-enforced, with Jofra Archer and Jack Leach primed to replaced James Anderson and Moeen Ali.
"We're one-nil down, but there's four matches to go in the series," said Buttler, speaking at a Kookaburra event at Lord's. "Test cricket is hard - you're playing against the best players in the world.
"If you're not good enough for long enough, then you're not going to win the game. But we've got a fantastic team … nothing really changes. We've lost that game, but we come here with a lot of excitement and belief that we're a good enough side to win this Test and make it one-all."
Despite the heavy margin of defeat, there were positives for England in their win, not least the first 45 overs of Australia's first innings, and Rory Burns' maiden hundred.
And Buttler emphasized that England had not been completely outplayed from first to last at Edgbaston.
"My view is we didn't play well enough for long enough, really," he said. "The first couple of days especially, we played a lot of really good cricket, and got in a really good position. Any time you lose James Anderson is a huge moment in the game, isn't it?
"Not being able to take those two wickets quicker [from 122 for 8] was obviously a huge part of the game. Steve Smith played an excellent innings. That's Test cricket - you're playing against great players.
"We know how Test cricket generally happens in England: there can be periods of the game that tend to meander along and then periods that happen very fast. If you look back to the India series [last summer], the big moments in those games we managed to get out on the right side and play well - that will be the same throughout this series."
Buttler struggled with the bat at Edgbaston, as he was dismissed twice by Pat Cummins for single-figure scores, but says he feels he is "not far" from his best form.
"I've felt in good form for 18 months or so. I feel like I'm the best version of myself that I've ever been, so I take a lot of faith from that. I'll prepare well, and give myself the best chance."
Several of England's World Cup winners have opened up about the emotional comedown after the drama of the final, with Ben Stokes and Liam Plunkett both revealing that they had struggled in the days immediately after.
And while Buttler hinted at having similar thoughts, he said it was important to "accept your emotions" to come to terms with the squad's achievement.
"A lot of people invested a lot into the World Cup, not just in the tournament but in the time before. Obviously people had never experienced that before [but] sport always moves on, doesn't it. Certainly for me it was nice to have a bit of time away to let what happened sink in and get energized for the next challenge."
Buttler knows the two men likely to come into the England team better than most - he has spent the last two IPL seasons in the same squad as Archer, and first played with Leach for Taunton Deane under 11s - and expects both of them to succeed.
"I'm excited for [Leach]," he said. "He's worked very hard to be in the position he's got himself into. He'll come in and he's a great person to bring into the team. He brings a lot of energy, a lot of skill with the ball, and he'll be excited for the challenge. I'm sure he'll be looking forward to batting at Lord's again."
Archer proved his match fitness by bowling 31 overs for Sussex's seconds this week, and after ending the World Cup as England's leading wicket-taker, it might be expected that there would be big expectations on his shoulders.
But Buttler played those down, and suggested that Archer would be able to shut out any outside noise. "Certainly not from within, there's no big expectations on him," he said, "but he tends to cope with those things quite well.
"He's a pretty laid-back character who has an immense trust in his game, so if he gets his chance I expected him to perform really well."
Buttler also played down the decision to give the vice-captaincy back to Stokes. Buttler had taken on the role last summer ahead of the India series, but said it had always been the plan to relinquish it when Stokes was ready.
"I enjoyed it. They said to me in time they'd like Ben to do the role again when he can, so I was very aware that was the situation, and the natural thing to happen.
"It doesn't really change a lot for me: I'm always willing to offer advice and I'm there if Joe wants to talk to me as are a lot of other players in the team as well who aren't vice-captain. It doesn't change a lot." AGENCIES