Rugby: Concussion keeps Sonny Bill Williams on sidelines

Sonny Bill Williams will be available for the Chiefs next week. Photo / Getty

Sonny Bill Williams will miss the Chiefs' encounter with the Sharks but the second-five is symptom-free after suffering concussion last weekend.

That mixed piece of news arrived as Dave Rennie made four changes to his run-on XV for the clash in Durban, with the personnel switches coming in the front row and the midfield.

Williams sustained two knocks to the head during last week's win over the Stormers, leaving the field and passing initial concussion tests before returning to help the Chiefs to a 28-19 victory in Cape Town.

But the All Black experienced headaches the following day and, although they quickly subsided, he was left with insufficient time to fulfil the five-day concussion protocol system a player must pass before returning to action.

"It's pretty minor," Rennie said. "He was a little bit dusty on Sunday, as you would be after taking a head knock and getting a cut under his eye following that. But he's been pretty good since then.

"You've got to go through a series of protocols and we've got to the stage now where he might just sneak in, but we decided to make a call and we didn't want to risk it. So we'll get him right and he'll be available for the Cheetahs (next week in Hamilton)."

Williams' absence will see Andrew Horrell start at second five, while Seta Tamanivalu completes a new midfield combination after replacing the injured Tim Nanai-Williams.

A broken finger saw Nanai-Williams head home from the Republic as the Chiefs, with Charlie Ngatai also on the sidelines, took a serious hit to their midfield stocks. But the depth in their squad has minimised any disruption and Tasman utility Tom Marshall will provide cover off the bench.

"It's a great opportunity for Seta," Rennie said. "Andrew Horrell comes back in and he's had a lot of experience for us in midfield. We'll have Tom Marshall covering that area as well, obviously with Charlie, Sonny and Tim out. It leaves us a little thinner but we're pretty lucky that we've got good cover there."

Aside from the midfield, the only other changes after last week's impressive effort are in the front row, with the scrum the sole area of concern to come out of the Stormers game.

One switch is injury-enforced, with Pauliasi Manu's damaged ribs preventing his involved, but the inclusion of Jamie Mackintosh and Siate Tokolahi is also reward after that pair helped to solidify the scrum in the second half.

"Pauli injures his ribs very early in the game and he tried to work his way through it," Rennie said. "But, in the end, our scrum got destroyed early and in hindsight he should've come off a lot earlier.

"His ribs are getting a lot better but we decided not to risk him this week. All things going well he'll be available for the Cheetahs next week."

Chiefs team to play the Sharks in Durban on Sunday morning (NZT):

Damian McKenzie, Bryce Heem, Seta Tamanivalu, Andrew Horrell, James Lowe, Aaron Cruden, Brad Weber, Michael Leitch, Sam Cane, Liam Messam (c), Michael Fitzgerald, Matt Symons, Siate Tokolahi, Hika Elliot, Jamie Mackintosh

Reserves: Rhys Marshall, Ben Tameifuna, Mitchell Graham, Michael Allardice, Johan Bardoul, Augustine Pulu, Tom Marshall, Hosea Gear