Lentjes has today been named in the troublesome No 7 jersey for the semifinal against the Waratahs in Sydney.
He replaces Dan Pryor, who badly injured an elbow in the stirring playoff win over the Chiefs last weekend.
Lentjes had a handful of games for the Highlanders this season before returning to play for his Taieri club in the Dunedin premier competition.
He is effectively the fourth-choice openside, with John Hardie and Shane Christie also sidelined with injury.
His inclusion is the only change to the Highlanders XV that beat the Chiefs.
There are two changes on the bench. Effervescent lock Joe Wheeler returns from a lengthy injury break, and Trent Renata replaces Marty Banks, who sustained a head knock last weekend and has been ruled out after concussion tests.
The visitors may have one less Waratahs gamebreaker to deal with on Saturday night.
Mercurial playmaker Kurtley Beale has been left out of the Waratahs squad for the game after failing to complete training today.
Beale had been restricted to light duties as he battled to overcome a quadriceps injury.
However, earlier reports suggested Beale would have a fitness test tomorrow to see if he was capable of playing against the Highlanders.
Halfback Nick Phipps told Australian media he expected Beale to play.
Matt Carraro has been named to start at second five-eighth.
Highlanders
Brendon Edmonds, Liam Coltman, Josh Hohneck, Alex Ainley, Mark Reddish, Elliot Dixon, James Lentjes, Nasi Manu, Aaron Smith, Lima Sopoaga, Patrick Osborne, Richard Buckman, Malakai Fekitoa, Waisake Naholo, Ben Smith. Reserves: Ash Dixon, Daniel Lienert-Brown, Ross Geldenhuys, Joe Wheeler, Gareth Evans, Fumiaki Tanaka, Trent Renata, Shaun Treeby.
Waratahs
Benn Robinson, Tatafu Polota-Nau, Sekope Kepu, Will Skelton, David Dennis (C), Jacques Potgieter, Michael Hooper (VC), Wycliff Palu, Nick Phipps, Bernard Foley, Rob Horne, Matt Carraro, Adam Ashley-Cooper, Taqele Naiyaravoro, Israel Folau (VC), Replacements (one to be omitted): Tolu Latu, Jeremy Tilse, Paddy Ryan, Mitchell Chapman, Stephen Hoiles, Patrick McCutcheon, Brendan McKibbin, Jono Lance, Peter Betham.
