It was a thriller, especially won by Struff 7-6 (5), 6-7 (6), 7-6 (7) and a reminder of the ongoing quality of this event.
Especially after all the hand wringing earlier this week following the absence of some of the bigger names, including Tomas Berdych, Roberto Bautista Agut and Gael Monfils.
Those who were questioning the withdrawals don't understand the realities of professional tennis.
And those who were debating the strength of the field don't know how good we have it.
Firstly, although Berdych and Monfils in particular were losses, it's part of the sport and happens every year, especially if players have a strong tournament the week before.
And others storylines always emerge. Cameron Norrie has been a focal point.
In terms of the quality of the field - in the immortal words of Fred Dagg - "We don't know how lucky we are".
The men's ASB Classic had 15 of the top 60 players in the world in the main draw, plus a qualifying field featuring several others in the top-100. Look at golf, the other major global individual sport.
The organisers of New Zealand's major golf tournaments would be doing cartwheels if they even got a few names in the top-100 to come here. It just doesn't happen. And players in the top-20? No chance.
Golf would kill for their equivalent of Struff (world No58), Tennys Sandgren (No61) or Taylor Fritz (50).
But it's not possible because, unlike in tennis with the Australian Open, there is no major to lure them to this part of the world.
The ASB Classic has its niche, and as demonstrated by Struff and Carreno Busta, can produce unbelievable contest when least expected.
Carreno Busta saved nine break points in the first set alone, including four consecutive set points in one service game, which stretched for 11 minutes.
After the players had split consecutive tiebreakers, the final set was a beauty.
Carreno Busta twice broke the towering Struff - who was serving bombs in excess of 215km/h - but couldn't hold.
The penultimate game of the final set was the best of the match.
Carreno Busta fended off four match points in a row, with a remarkable display of composure under pressure, before flashing a backhand winner down the line to take the game.
The subsequent tiebreak had more twists, with both player having match points, before Struff finally converted his seventh in the 180th minute of an epic encounter.
