But he is expecting a backlash from what will be a fired-up Waikato side.
Donnelly, who is in his second year with the Otago side, looking after the forwards, said it has been an awesome year for him.
"It's great. Being in a team environment and getting all the benefits of that but not having to worry about playing," he said.
"Last year was a massive challenge for me. I had only just finished playing and then quickly had to think about coaching. I have learnt from that.
"It's like anything. You do a little bit more then the better you get."
Donnelly felt he had improved in getting the messages through to players concerning the game and the players had responded.
The Otago forward pack has been in impressive form throughout the season, growing stronger as the season has gone on.
The men up front played particularly well against Waikato in the Ranfurly Shield challenge a fortnight ago and Donnelly (37) said the defensive work of the forward pack has been exceptional in that game.
"But that was two games ago now. You are only as good as your last game.
"We defended their lineout quite well in that game but we had done a lot of preparation into that part of the game that week. But the final is a different game. These games often come down to key moments."
Donnelly has played in plenty of big games over the years and knows composure and taking the chances which come along are key.
The lineout has had a bit of study this week after Hawke's Bay won some Otago throw-ins in the semifinal last Saturday.
He said the Magpies had a very good defensive lineout which was hard to combat but was confident the Otago set piece would be right tonight.
The side relied on lock Josh Dickson a lot at lineout time and the rangy second rower has come to the party throughout the season.
Donnelly did not play for Otago in the 2012 or 2016 finals as he was overseas at the time.
He said he would think about his coaching future after the final in Hamilton.