Rugby: Sonny Bill Williams looming as starting No 12 for All Blacks

Sonny Bill Williams of the Blues during an Auckland Blues Super Rugby training session. Photo / Getty Images.

The midfield is looming as perhaps the biggest unknown for the All Blacks over the next six weeks and while Sonny Bill Williams suffered a knee injury during the Blues draw against the Chiefs at the weekend, he showed he is approaching top form and probably deserves to start in the first test against the British and Irish Lions.

He will have the potential to play two more matches for the Blues before that first test on June 24 - against the Reds in Apia on Friday, and against the Lions at Eden Park five days later on Wednesday next week - but, now that Tana Umaga's men are officially out of the Super Rugby playoffs, the Blues may elect to play him only in the latter.

They will probably take a conservative approach because they will be desperate to start Williams at second-five against the Lions, a match obviously significant for everyone involved.

The 31-year-old has been building since his return from an Achilles injury suffered last year, a comeback halted by a concussion which ruled him out of his team's victory over the Cheetahs just over a fortnight ago.

But he showed during his 56 minutes against the Chiefs, one of his former teams, that he is nearing his best. His early wrestle with opposite Johnny Faauli suggested he was up for the physical stuff and he didn't disappoint there; he was more direct than at any other time this season and his offloading game was back too.

If Williams is fit following the Blues v Lions match, he will almost certainly get plenty of game time in the All Blacks' test against Samoa at Eden Park on June 16, a match designed to get Steve Hansen's men physically and mentally ready for the three-test series against the Lions.

If so, it will be Williams' first for the national team since the World Cup final in 2015.

Chiefs coach Dave Rennie described Williams as a "handful" after his team's 16-all draw at Eden Park, and the big No12 has the potential to create serious problems for Warren Gatland's men.

Ryan Crotty must be odds-on to partner Williams in the first test. Rested for the Crusaders' recent victory over the Rebels in Melbourne after suffering from concussion in the match against the Chiefs in Suva, Crotty is in outstanding form.

His decision-making and defence has again been consistently excellent and he must be considered one of the best distributors at Hansen's disposal.

Others in the mix will be Malakai Fekitoa, George Moala and Anton Lienert-Brown, but the first two, while probably more direct that Crotty, lack the vision on attack that he has and Lienert-Brown is yet to recapture his form of last season.

Ben Smith, back to his best for the Highlanders after ankle trouble, must be the favourite to start at fullback, while the All Blacks coaches will back themselves to get the best out of wings Julian Savea and Waisake Naholo.

Hooker Dane Coles will start if he is fit, and that's a big unknown too following his concussion troubles, with the loose forward mix also providing potential for debate.

Jerome Kaino, Kieran Read and Sam Cane should make up the loose forward mix if healthy, but Kaino's knee issue and Read's broken thumb complicate matters. Both will be considered for the first test even without any game time.

Liam Squire is the obvious candidate to replace either Kaino or Read, but his own broken thumb means Scott Barrett could be a possibility to start at No6 against the big Lions pack.

Should that be the case, Luke Romano could go on to the bench.

Jordie Barrett, yet to make his test debut, must be considered a bench chance for his ability to cover midfield to fullback and goalkicking excellence.

Possible All Blacks' match-day squad for first test against British and Irish Lions at Eden Park on June 24: Ben Smith, Waisake Naholo, Ryan Crotty, Sonny Bill Williams, Julian Savea, Beauden Barrett, Aaron Smith, Kieran Read (c), Sam Cane, Jerome Kaino, Sam Whitelock, Brodie Retallick, Owen Franks, Dane Coles/Codie Taylor, Joe Moody. Reserves: Codie Taylor/Nathan Harris, Wyatt Crockett, Charlie Faumuina, Scott Barrett, Ardie Savea, TJ Perenara, Aaron Cruden, Jordie Barrett.