Having knocked off the world No1 duo, the Queenstown doubles specialist is preparing for today's Australian Open semifinal alongside German partner Jan-Lennard Struff.
That will be against Austrian Oliver Marach and Croatian Mate Pavic.
Coming off the biggest win of his career, you now have to think he is capable of winning the whole thing.
He is not looking too far ahead, though.
''I mean definitely still taking it one match at a time, got to focus on the next one,'' he told the Otago Daily Times from Melbourne.
''I guess everyone's playing well now. Everyone's in the semifinals so it's going to be a tough match no matter who we play.''
Tuesday's quarterfinal could not have been closer.
Both the second and third sets went to tiebreaks, with neither side getting broken.
While he said it would have been good to take the chance to win in straight sets, it was awesome to get through.
That was despite a twisted ankle, which he had taped up late in the first set.
It had a ''little bit'' of an impact, but it came right by the end and the adrenaline got him through.
It was now feeling fine.
He felt both he and Struff came up with some big plays in the final tiebreak.
Neither showed any sign of nerves, although he said the tense moments did cause things to go to another level.
''The intensity definitely rises and your instincts kind of take over there in the big moments.
''Sometimes after a point you realise 'woah, that was a great point'.''
Perhaps it all comes back to form in those moments.
Clearly that is working in McLachlan's favour, as he and Struff have barely put a foot wrong.
''I mean I feel good out there.
''The last match my partner played really well, which was huge, and the match before that I felt like I played really well.
''Hopefully, we can just keep it going, just come out and bring the same stuff we've brought out the last few matches.''
Bringing that same stuff started yesterday, as he looked to prepare for today's match exactly the same way he had been.
He had a pratice but spent most of the day resting up.
His coach, older brother Riki, had watched yesterday's semifinal to get a scouting report on their opponents.
It was the first time he and Struff had played together, having only met in person last week before the first match.
Playing more together could be an option, although that would depend on what happens with their rankings and also Struff's singles, in which he is ranked 55th in the world.
