The All Blacks hooker injured his ribs in the 41-0 quarter-final victory over South Africa's Sharks last week but coach Chris Boyd has been in no hurry to make a final ruling on whether Coles will play in the all-New Zealand clash.
"Colesy is doing everything he can to get himself fit in time for kick off, but at the end of the day we just won't know until a little closer to kick off," Boyd said.
"We are hopeful he'll make it to the start line."
Proudly Wellingtonian, Coles has been the beating heart of a mobile and aggressive Hurricanes pack which has dominated the collisions and proved equally strong in set phase this year.
The strength of the forwards has allowed the halfback duo of scrumhalf TJ Perenara and flyhalf Beauden Barrett, arguably playing the finest rugby of their careers, to get the best out of their inexperienced backline.
The Chiefs beat the Hurricanes 28-27 in Wellington on April 23 but the home side's performance was such that Chiefs co-captain Sam Cane admitted afterwards he had no idea how they had managed to sneak the victory.
Since that loss to the Chiefs and another to the Sharks two weeks later, the Hurricanes have been the model of consistency, combining bruising defence with potent attack to top the regular season standings and reach a second successive semi-final.
They have won their last six games and scored more than twice as many points as their opponents (197-88), indicating they are peaking at the right end of the season.
The twice champion Chiefs were the early form team of New Zealand's tough conference this year, winning seven successive games before a loss to the Highlanders in early May.
A 45-25 thrashing by the New South Wales Waratahs before the June international break, however, showed they were vulnerable against a side willing to take them on up front and test them out wide.
Their squad has also been sorely tested by a raft of injuries to key players.
Dave Rennie will undoubtedly field his strongest available side on Saturday with Cane, who was substituted following a head knock in their 60-21 win over the Stormers last week, and injured centre Seta Tamanivalu (knee) both starting.
The other finalists will be decided when South Africa's Lions host the reigning champion Otago Highlanders in Johannesburg later on Saturday.
(Editing by Nick Mulvenney)
