If size is what the Chiefs are after when it comes to backline strike power, then they have it in spades after unveiling a formidable line-up including the return of dual international Sonny Bill Williams.

After a two-year sojourn, Williams returns to the Chiefs fray with a 38-man squad announced today tasked with vying for their third title in four years.

Sonny Bill Williams on the charge against the Crusaders in 2012. Photo: Tracy Hardy.

The 19-test All Blacks is joined in the midfield by newcomer Seta Tamanivalu alongside established names like Charlie Ngatai, Tim Nanai-Williams and Andrew Horrell.

The inclusion of Williams and Tamanivalu sees Robbie Fruean squeezed out of the midfield equation, re-signing with the Crusaders for 2015.

Out-wide winger Hosea Gear is returning to New Zealand after playing in France and Japan, while Tasman wing Bryce Heem joins teammate James Lowe in the squad.

New Zealand-born Japanese national captain Michael Leitch also returns to the Chiefs having been a member of the squad in 2013.

Versatility continues to be the Chiefs strong suit, as they opt for the 38-man squad as opposed to the official 32 main squad and six wider training group members.

And joining the All Blacks-laden Bay of Plenty contingent in the squad is flanker Johan Bardoul, who forced his way in after an impressive ITM Cup campaign.

Bardoul will be alongside Sam Cane, Brodie Retallick and Nathan Harris, keeping the Bay quota at four after Tanerau Latimer's departure to Japan at the end of last season.

Chiefs coach Dave Rennie believes they have a squad high in character with impact, depth and versatility.

He says: 'We expect this group of hard working men to play a brand of Chiefs rugby that is entertaining for people to watch and will get results.”

'We are pleased that our squad contains a number of players coming through our Chiefs development programme [five players] who are making the step up to Super Rugby.”

Those players are Bardoul, Tamanivalu, Waikato's Damian McKenzie, Toni Pulu and Maama Vaipulu from Counties Manukau.

The numbers breakdown of the 2015 squad shows there are 23 returning Chiefs players, with 21 of those from last year.

There are a further 16 players from other Provincial Unions and two players returning from playing in Japan. Ten of the Chiefs squad played in the thrilling ITM Cup final that was won by Taranaki - one of the six Provincial Unions making up the Chiefs.

Chiefs halfback Tawera Kerr-Barlow, who was injured during a recent All Blacks match, will continue his long-term rehabilitation with the squad.

2015 Chiefs Squad

Ben Afeaki – Prop (North Harbour) Michael Allardice* – Lock (Hawkes Bay) Johan Bardoul* – Loose forward(Bay of Plenty) Sam Cane – Loose forward (Bay of Plenty) Aaron Cruden – First Five-eighth (Manawatu) Mike Fitzgerald – Lock (Manawatu) Leon Fukofuka* – Halfback (Auckland) Hosea Gear* – Winger (Chiefs) Mitchell Graham* – Prop (Taranaki) Nathan Harris – Hooker (Bay of Plenty) Bryce Heem* – Winger (Tasman) Andrew Horrell – Utility back (Hawkes Bay) Tevita Koloamatangi – Loose forward (Tasman) Michael Leitch – Loose forward(Chiefs) Anton Lienert-Brown – Midfield (Waikato) James Lowe – Winger (Tasman) Pauliasi Manu – Prop (Counties Manukau) Tom Marshall – Utility back(Tasman) Rhys Marshall – Hooker (Taranaki) Damian McKenzie – First five-eighth/fullback (Waikato) Quentin MacDonald* – Hooker (Tasman) Jamie Mackintosh – Prop (Southland) Marty McKenzie* – fullback/first five-eighth(Taranaki) Liam Messam – Loose forward (Waikato) Charlie Ngatai – Midfield/fullback (Taranaki) Sean Polwart *– Loose forward (Auckland)Brodie Retallick – Lock (Bay of Plenty) Augustine Pulu – Halfback (Counties Manukau) Toni Pulu* – Winger (Counties Manukau) Liam Squire – Loose forward(Tasman) Matt Symons – Lock (Canterbury) Seta Tamanivalu* – Midfield (Taranaki) Ben Tameifuna – Prop (Waikato) Siate Tokolahi* – Prop (Canterbury) Maama Vaipulu* – Loose forward (Counties Manukau) Brad Weber – Halfback (Waikato) Sonny Bill Williams – Midfield (Counties Manukau) Tim Nanai-Williams – Utility Back (Counties Manukau) *new to Chiefs squad