But the loss of Lentjes has been tempered by experienced loose forward Adam Thomson coming back into the starting side.
Lentjes left the field in the opening quarter of last week's game against North Harbour after taking a blow to his leg as he attempted a tackle.
He has been diagnosed with a grade three injury to the medial collateral ligament in his knee and is out for eight weeks.
Otago coach Ben Herring said it was an unlucky injury for Lentjes who was walking around in a large knee brace yesterday.
Halfback Kayne Hammington is also out for this week as he continues to come back after dislocating his big toe.
Rowan Gouws will continue as starting No9 with Connor McLeod in the reserves.
Jona Nareki comes back on to the left wing while Taylor Haugh is in the reserves.
Mika Mafi will play his 15th and blazer game for Otago if he comes off the bench.
Waikato will finalise its team today. Key playmaker and former Otago player Fletcher Smith is battling a shoulder injury and will be a big loss if he does not front.
Skipper Dwayne Sweeney played his 100th game for Waikato last weekend.
Waikato lost 35-26 to Tasman last week and needs a win to get back into the playoff race of the Mitre 10 Cup Premiership.
Otago v Waikato
Forsyth Barr Stadium, tomorrow, 2.05pm
Otago: Michael Collins (captain), Vilimoni Koroi, Aleki Morris-Lome, Sio Tomkinson,
Jona Nareki, Josh Ioane, Rowan Gouws, Dylan Nel, Slade McDowall, Adam
Thomson, Josh Dickson, Joe Latta, Hisa Sasagi, Nic Souchon, Aki Seiuli. Reserves:
Sekonaia Pole, Jonah Aoina, George Bower, Louis Conradie, Mika Mafi, Connor
McLeod, Taylor Haugh, Henry Purdy.
Waikato (probable): Solomon Alaimalo, Declan O’Donnell, Quinn Tupaea, Dwayne
Sweeney (captain), Bailyn Sullivan, Fletcher Smith, Jack Stratton, Simon Parker,
Mitch Jacobson, Hamilton Burr, James Tucker, Api Naikatini, Sefo Kautai, Samisoni
Taukei’aho, Rob Cobb. Reserves: Sam Cooper, Ollie Norris, Josh Iosefa-Scott, Tim
Bond, Murray Iti, Carlos Price, Rivez Reihana, Matty Lansdown.
Referee: Richard Kelly (Taranaki)