With a 77-point cushion over his nearest rival in Ferrari's Fernando Alonso, Vettel could conceivably make it four in a row on Sunday in Suzuka, the scene of his 2011 championship success.
Should Vettel achieve the feat, either in Japan or the double header in India and Abu Dhabi that follows, the 26-year-old will become the youngest four-time winner in the sport's history.
Of the three other quadruple championship winners, Juan Manuel Fangio was 45 when he claimed his fourth crown, whilst Alain Prost and Michael Schumacher were 38 and 32 respectively.
"If we are to achieve it, then it would be massive," said Red Bull team principal Horner.
"To win it the first time was special, to defend it was remarkable, and we never thought we could surpass the triple.
"If we get a fourth, it would be something the whole team would be blown away by. It would be phenomenal."
Naturally, the prospect of a fourth title is a tantalising one, not that Horner is allowing his mind to contemplate such a prospect.
"We have not allowed our thoughts to drift, we are not thinking about the championship. We have stayed in the moment and stayed focused," insisted Horner.
"If the moon and stars align and he wins the race and Fernando is ninth or below, then theoretically he can win the championship.
"But our approach in Suzuka will be the same as in our other races this year in that we will go there to get the best out of ourselves, and the championship will tend to take care of itself.
"So long as we win it, I don't care where we win it, but the chances of us winning it in Suzuka are low. When does Fernando Alonso ever not finish a race?
"He is driving supremely well at the moment, and with discipline. He is on a great run.
"So we are going to push to the end of this championship, right up to the chequered flag in Brazil (the final race).
"Because we cannot control what others do, we just need to push ourselves, which is what we will do."
Ironically, Alonso failed to finish last year's Japanese Grand Prix after suffering a first-lap accident, whilst Vettel went on to take the chequered flag, the scenario required that would see the latter become champion again.
It was the German's third victory in four years at Suzuka where he has also been on pole for the last four races.
Despite such dominance, not just in Japan but overall in F1, Horner maintains that "winning never gets boring".
To the fans, and as Lewis Hamilton remarked this week, Vettel may be sending everyone to sleep with his performances, but for Horner the hard work, will and determination within the team are second to none.
"To win races takes so much effort from all the departments behind the scenes," added Horner.
"All the guys and girls back at the factory in Milton Keynes are working flat out.
"We had Adrian Newey (chief technical officer) back in the operations room supporting the team through all of the sessions.
"So he was a virtual attendance at the grand prix, like he was on the pit wall, but he wasn't there.
"And it is down to that type of teamwork, and the effort that goes on behind the scenes that we are able to achieve the kind of results we have over the last four or five years."