Coles has been out of the game since March, but played 30 minutes off the bench against the Brumbies last weekend.
Assistant coach John Plumtree says he's recovered well from that game.
"He's good to go - there's a good chance you'll see him start he's got his spark back and obviously it's a big game for him and a big game for the club this weekend."
It would be Coles' 100th Super Rugby game if he takes the field.
Meanwhile midfielder Vince Aso is also expected to return to the starting lineup after missing the quarter-final through injury.
That would mean Jordy Barrett would return to fullback.
"I think Vince and Ngani play great footy together that partnership is ticking along nicely, Jordie did a great job filling in at 13 but we'll be looking after Vince well this week to make sure he is good to go," Plumtree said.