Thomas said a recent cricket played on the grounds was believed to have created bare patches in the turf and could have led to some player welfare concerns.
"We were caught a bit unawares that the field had been affected by the cricket. But we've worked very hard now with the teams, the referee, and everybody at the venue to ensure the match will go ahead."
Recent inspections showed the field was soft enough to play on.
Thomas said he could not comment on reports of a potential fine for Napier City Council - as the venue owners.
"As far as we're concerned the most important thing at the moment is that we have a match, and the match is being played, and McLean Park will be hosting it. That's the first issue, we will then be looking at the whole matter.
"We do review all of these issues when they occur, we have weekly reviews and yearly reviews about the venues and pitches, so we'll be taking into consideration those but as to any further action, I can't possibly comment at this stage."
A Hurricanes spokesman said they had been taking advice on the pitch, but both they, and the Sharks were fine to play on it.
"The groundsmen and the council have given us their assurances that it'll be fine," he said. "As far as we're concerned the referee's have signed it off...and both teams are happy to play".
Napier City Council chief executive Wayne Jack was confident the field would be presented in "top notch condition" for tonight's game, and that any issues with the park would be resolved in its upcoming returf.
"There was Plunket shield cricket played on it last week, so it was prepared for cricket and the team have turned it around within a week. The main issue is that [the field's] safe to play on, which it is."
He said they were not expecting any fines, or further action to be taken against the council.
This is the latest in a spate of issues for Napier's premier sporting venue, starting after a one-day cricket international between New Zealand and Australia in February last year was abandoned without a ball being bowled.
When asked how another McLean Park issue looked for Napier's ability to host sporting events, Napier Mayor Bill Dalton pointed to their $4.9million redevelopment of the park which begins next week.
"That's why the bulldozers are in there on Monday, to completely dig the park out and replace it, that's why because there are some problems with the park.
"We're dealing with that … it's in our long term plan. We're going to end up probably by the time we've finished with the best multi-sports park in New Zealand."
NZRPA CEO Rob Nichol said he would have been surprised to see how the ground could not be up to scratch, as the game had been scheduled for awhile.
"The main concern from a players perspective, and a teams perspective is welfare stuff, so I'm sure [SANZAAR] will be all over it, they've got a pretty long track record of managing these kind of fixtures.
"Hopefully it works out all right. The last thing Napier needs is another grounds controversy for a high profile sporting event."
Hawke's Bay Rugby Union chief executive Jay Campbell said he was not aware of any current issues that would affect the game going ahead.
This will be the last match at McLean Park before excavators move in to rebuild the oval with a new drainage system, a drop-in cricket block and a new hybrid turf.
The hybrid turf is being grown in Auckland, and is due to be harvested and transported to Napier in July. It is hoped the venue will reopen in time for the spring rugby season - as long as the weather plays ball.
The high-tech hybrid turf will ensure flexibility in McLean Park's use, being resilient enough to be able to host sports games, large-scale music gigs, and all sorts of community events.
Other improvements to the park include improved irrigation and sub-soil drainage, cricket practice nets, a weather station and moisture sensors to allow for selective irrigation, meaning areas of the ground would not be over-watered.
Over summer drainage issues meant three scheduled international cricket matches were moved from McLean Park, and Central Districts scheduled most summer games away from the venue.
