The Chiefs are holding open a midfield spot for the 2014 season, with Williams - currently playing in the NRL for the Sydney Roosters - in mind, and he is considered almost a certainty to return to Hamilton for the World Cup year of 2015.
"At this stage we haven't filled up our midfield roster so if he was available we'd certainly jump at that opportunity," Rennie said of next season.
The defending champion Chiefs, second on the table with the chance to go to first if they beat the Hurricanes in Hamilton on Friday night, have had a mix-and-match look to their midfield this season.
Richard Kahui's shoulder injury and looming departure for Japan - he is set to formally sign a contract with Toshiba this week after getting the all-clear on his problem joint - has meant Tim Nanai-Williams, Bundee Aki, Andrew Horrell and Charlie Ngatai have been swapped around the second-five and centre positions.
None, apart from Ngatai, are particularly large men, with Aki and Nanai-Williams, the midfield partnership against the Hurricanes, one of the smallest in Super Rugby. Williams is an imposing physical presence in the No12 jersey, an attribute which goes hand in hand with his offloading skills.
Some of the Chiefs management met with former All Black Williams - a revelation with the Chiefs last year - when in Sydney for the Waratahs match in April, but it's Rennie's confirmation that he is leaving a spot open for Williams next season which is most significant.
"We spent quite a bit of time with him," Rennie said. "It was test week and the Roosters weren't playing. He's been in bloody good nick and in good spirits. He enjoys the boys, he spent a lot of time around the hotel and so on, so it was good to catch up with him from that point of view."
Rennie said Williams was concentrating on the Roosters but gave positive vibes about a return next year, adding that the 27-year-old's controversial manager Khoder Nasser had given the same message.
"One thing with Khoder is that I really enjoy working with him because he is straight up. If he says something is going to happen then it happens and I find those sorts of people bloody good to deal with.
"He was outstanding to work with last year. I know people paint a picture of him being difficult but he's doing his best for his client, I guess. We found him really easy to work with. He's not greedy and he's not difficult in any way."
All Blacks lock Brodie Retallick has made a quick recovery from his hamstring injury suffered before the test against France in Christchurch a fortnight ago and will return for Rennie's men against the Hurricanes.
Nanai-Williams has recovered from his stomach ulcer and the break had also given him time to rehabilitate a groin problem, Rennie said.
The Chiefs have a longer lay-off than the other New Zealand sides due to their bye before the test window, but Rennie said the break shouldn't hurt them.
Last week at Waikato Stadium the Chiefs had a 40-minute hit-out against a Counties team followed by another 40 minutes against a Bay of Plenty side.
"It's a mindset thing," he said. "If you think it's a distraction and an issue then it probably will be, but this is where we want to be. We've got ourselves in a good position and there's only six weeks left in this competition. It's a chance to throw everything at it."
No8 Ross Filipo is available again after his knee injury, with fullback Gareth Anscombe recovering from his broken foot and a possibility for next week's match against the Crusaders in Christchurch.
The Chiefs team to play the Hurricanes at Waikato Stadium on Friday, kick-off 7.35pm is: Robbie Robinson, Lelia Masaga, Tim Nanai-Williams, Bundee Aki, Aseali Tikoirotuma, Aaron Cruden, Tawera Kerr-Barlow, Matt Vant Leven, Tanerau Latimer, Liam Messam, Brodie Retallick, Craig Clarke (c), Ben Afeaki, Hika Elliot, Pauliasi Manu. Reserves: Mahonri Schwalger, Ben Tameifuna, Michael Fitzgerald, Sam Cane, Augustine Pulu, Andrew Horrell, Charlie Ngatai.
Hurricanes: James Marshall, Matt Proctor, Conrad Smith (c), Reynold Lee-Lo, Julian Savea, Beauden Barrett, TJ Perenara; Victor Vito, Karl Lowe, Brad Shields, James Broadhurst, Jeremy Thrush, Ben May, Dane Coles, Ben Franks. Reserves: Ash Dixon, Reggie Goodes, Mark Reddish, Faifili Levave/Blade Thomson, Chris Smylie, Tusi Pisi, Alapati Leiua.
