Even that seems a negative leap of faith.
Depending on if he remains in the field for next week's Shell Houston Open, Johnson may well be playing at Augusta National to extend his winning streak to four events. "You had better ask them", was the characteristically low-key reply.
These are the words of a player who went 112 holes this week and never trailed. And he joined Greg Norman and Vijay Singh, a couple members of the World Golf Hall of Fame, as the only players to win their first two events after becoming No. 1 in the world. He is now the holder of three out of the four.
However his five WGC titles pale in comparison to Tiger Woods' phenomenal tally of 18.
"Jon played really well but, as I said, I really didn't give him anything".
"But it was tough out there as the greens were really fast and the wind was affecting all the putts". Jon played really well.
United States 42nd seed Bill Haas held off a late charge by countryman Phil Mickelson to defeat the five-time major victor 2 and 1 and reach a Sunday semi-final against 22-year-old Spaniard Jon Rahm, the 21st seed who routed Denmark's Soren Kjeldsen 7 and 5.
Johnson hung in there all the way to the 18th, and closed out Rahm, 1 up. Honestly, he doesn't really make mistakes.
Both pared the last for Johnson to also claim his 15th PGA Tour win that now includes five WGC victories. "Confidence in my game and confidence in myself", he said. It will prove fascinating to watch how Rahm handles his Masters debut.
Johnson looked set to be cruising in his semifinal against the Match Play debutant when he was three up through seven holes at Austin Country Club, but the surprise package from Japan mounted a stirring fightback.
Johnson stretched ahead by winning four holes in succession from the 3rd tee. The Aussie has won the Match Play twice and the WGC-Cadillac Championship once.
Rahm had hoped to land the ball sufficiently close for a manageable birdie putt, which would have won him the hole and forced a three-hole play-off for overall glory.
When he missed the birdie putt, Rahm found himself just two down with thee to play and there was a sense the momentum was in his favour.
"It shows me that I can compete with someone like DJ and any other player, even if I had probably one of my worst front nines possible", Rahm said. Johnson duly made par as Rahm could do no better, leaving the world No1 as the champion by the most slender of margins.
He finished off his dream run with a win over Bill Haas in the consolation match to finish third and earn an invitation to the Masters next month.