Down 16-6 and looking under pressure, Waikato responded with a fabulous set move try in the 38th minute, centre Savenaca Tokula getting outside his opposite Michael Collins, and Tim Mikkelson finishing it off.
Similar work got Trent Renata over the line on halftime, but a harsh, almost inexplicable video call ruled the try out for a forward pass. It was a wonder that referee Glen Jackson even went to the fourth official.
The first half was stacked with clever endeavour punctuated by a couple of superb attacks, the first bringing Otago a 26th minute try to Parker.
Gareth Evans' breakdown expertise delivered the ball deep in his half, fellow loosie Lee Allan made a fabulous charge, Parker kicked cleverly, and the No 10 then finished off.
Parker, who nailed all his goals, certainly did all he could to write himself into Otago rugby folklore.
Controversy included Waikato lock Brian Alainu'uese's ridiculous late hit on fullback Tony Ensor which enabled Parker to land a key goal.
Otago 26 (Hayden Parker, TJ Ioane tries; Parker 4 pen, 2 con)
Waikato 19 (Tim Mikkelson try, Trent Renata 4 pen, con).
HT: 16-13.