The 23-year-old seems wary nonetheless, with some suggesting he alone could be the answer to all England's ills as Alastair Cook's team try to overturn a 1-0 deficit against India and halt a miserable run of seven defeats in nine matches.
Buttler's chance has arisen following Matt Prior's announcement, in the aftermath of Monday's Lord's defeat, that he will take the remainder of the summer off because of injury. After 69 limited-overs caps, dating back almost three years as he has established himself as a first-choice selection in short formats, Buttler is set to achieve his "ultimate goal" of a Test career.
His ability to turn matches on their head with clean, calculated and inventive hitting - especially after his brilliant maiden international hundred against Sri Lanka at Lord's at the end of May - has raised awareness of potential in Test cricket too.
He is wary of fuelling uneducated assumptions that he will simply turn up tomorrow at the Ageas Bowl - it stages the third Investec Test and, coincidentally, was the venue for his maiden first-class century four years ago - and immediately bail out ailing England with bat and gloves.
"I'm not coming in expecting to be the one person who can fix English cricket, unfortunately," he said. "It'd be great if I can. That would be brilliant. But I'm just coming in determined to be authentic, be myself, enjoy the occasion and look forward to helping England put in a performance."
Buttler admits it is an advantage not to have been a part of the team during their struggles up to now, while enjoying a familiarity with England team-mates as a limited-overs regular. "I come in pretty fresh," he said. "Obviously I haven't been involved in Test cricket before, so I come in without that baggage. For me, it's going to be such a great occasion and I'm determined to get the best out of myself on Sunday."
He will not be meeting any team-mates for the first time here. "I think that makes the transition a little bit easier for me," he added. "I know people and have built those relationships. I'm not coming in with a 'first day at school' feeling. Test cricket's still a step into the unknown, but it's one I'm determined to enjoy."
This weekend is the realisation of a lifelong ambition for a hugely-talented all-rounder, whose skills propelled him first into the short-format limelight.
After that Lord's hundred, a revelation to many, he insisted modestly he was not yet ready for Test cricket. That was little more than a month into his Lancashire career, Buttler having moved north from his native Somerset for the opportunity to be an inked-in county wicketkeeper.
He said: "Test cricket's been my ultimate goal for the whole of my career. It's probably come a little bit sooner than I thought it would, which is great. Mentally, I've come round to the fact I was closer than perhaps I thought I was at the time [seven weeks ago] - and my cricket has progressed faster than I thought. I was well aware I had just scored a hundred and it would have been easy to say 'I'm playing really well and I'm ready'. In the weeks since then, I've realised I was closer to playing than I thought I was."
He knows he will have to adapt yet must not lose the approach which has taken him all the way to the highest level. "Test cricket's going to be completely different," he said. "Naturally I want to score runs and hit the ball, and I don't think things should change that much. I have got to be a bit more selective and work out a method to bat longer, so I can put a few shots away that I might not need to play in Test cricket."
Not too many, the crowd will hope.