By Duncan Johnstone

New Zealand heavyweight boxer Joseph Parker is entering a dangerous phase in his rapidly blossoming career.

That's the view of veteran commentator Colonel Bob Sheridan.

The flamboyant American is in New Zealand to call Parker's fight with Sherman Williams on Thursday night.

Sheridan, who has been ringside for several of Williams' 52 fights, is adamant that the 42-year-old from the Bahamas represents a ''very dangerous opponent'' for Parker.

But if he can negotiate Williams, things will then get very interesting for Parker.

That's because the 22-year-old has come so far, so fast with the latest reward for his rapid development a No 11 ranking with the WBA to go with his No 14 position with the WBO.

It's a risk-reward scenario now that Sheridan feels is fascinating as Parker's handlers try to plot a way forward.

''Joseph Parker is going to have to start fighting some guys in the top 10 and that's really dangerous for him,'' said Sheridan who has broadcasted over 10,000 fights including more than 900 world title fights since the late 1960s.

But he warned against looking too far ahead and certainly felt ''Tank'' Williams, who has been knocked out just once and secured 36 wins around the world, shouldn't be taken lightly.

''The Tank has been in with some class fighters and never taken a beating.

''This guy has been down the road and he's tough. He throws booming overhead shots and I'm sure he will try to get to that shoulder,'' Sheridan said of Williams targeting the left shoulder of Parker that has been causing him problems over the last few days.''

Sheridan said Williams had made a living out of being an underdog and fighting in far-flung destinations. It was a situation he revelled in.

He also took a liking to ''roughing up'' opponents with an in their face style that was highlighted by his 2012 clash with heavyweight legend Evander Holyfield.

The WBF title fight had to be stopped in the third round because of Holyfield's left eye being cut from a clash of heads.

Williams said he was coming off a ''great training camp'' and was itching to finally get in the ring with Parker after their earlier fight in May didn't eventuate.

''I've been to New Zealand twice for promotional tours but I'm not here for a holiday now,'' Williams smiled.

''I here to win, I'll give him a proper beating.'' Parker said he was feeling 100 per cent after his should scare.

"Medical clearance and his own belief in his recovery had given him the confidence that the shoulder would be fine for Thursday night.

''I've treated it, looked after it ... I'm ready to go,'' Parker said.