British and Irish Lions flanker Sean O'Brien will join All Black Sonny Bill Williams before a judiciary panel on Sunday after being cited for allegedly striking Waisake Naholo during the second Test in Wellington.

O'Brien and Williams are both expected to miss the third and deciding Test in Auckland next week if found guilty.

O'Brien's swinging arm that floored Naholo midway through the second half "met the threshold for a red card", the citing commissioner said in a decision released several hours after Saturday's Test won 24-21 by the Lions.

Williams, who was sent off in the first half following a shoulder charge to the head of Lions wing Anthony Watson, and O'Brien will appear separately before an all-Australian judiciary panel on Sunday evening.

Naholo left the field after he was hit in the jaw, but All Blacks coach Steve Hansen said he showed no ill-effects the next morning.

Hansen confirmed Williams would not contest his red card and a suspension would rule him out of the third Test.

"There's a (judicial) process, we trust the process. Sonny's paid a big price. The team's paid a big price for him making a mistake," Hansen said.

Source: AFP