Just a few weeks ago Tearney's confidence had nosedived. He was top seed at the New Zealand Championships, but was blown away in the final by Artem Sitak, losing 6-2 6-0 in a nervy, hesitant display.
If that was a low point, this week has been a highlight. Tearney progressed through qualifying - the first Kiwi to do so since 2008 - beating World No 276 Cameron Norrie on the way.
Even though he was vastly overmatched on Monday - World No59 Haase has been ranked as high as No33 and has reached six ATP singles finals - the 26-year-old Wellingtonian continued the same proactive approach.
"[There are] still areas of improvement but I am trying to be aggressive, trying to come in and that is the way forward for me," said Tearney. "A positive step in the right direction."
Tearney went to an early 3-0 lead in the first set on Monday, but Haase was good enough to respond. His serve was a major weapon and he banged four consecutive aces - all down the middle - to close out the set.
"I wish I had that, that would be nice to be able to do that," said Tearney. "I was standing there and in about four seconds I was at the changeover - set over - after being up 3-0 10 minutes earlier."
In the second set Tearney again had a 3-0 lead - with some deft touches at the net and strong winners off the backhand wing - and had Haase under pressure at 15-40 on his serve in the fourth game.
"At that stage I was like okay, if I lose this game, this set is gone probably," said Haase.
"There were one or two great points there where I he could have finished it actually but then I managed to hold."
That was Tearney's big chance, and from there Haase turned the screws.
But it was an impressive effort from the Kiwi - much better than last year's match against Donald Young - and gives a solid platform for this year.
"I'm a bit gutted I lost but I'm happy with the tournament overall," said Tearney.
Seventh seed Steve Johnson progressed to the second round with a comfortable 6-4 6-3 victory over Stephane Robert while 2015 champion Jiri Vesely trumped Argentinean Horacio Zeballos 6-4 6-3.