Rugby: Sonny Bill Williams socks Blues teammate Blake Gibson in the face

It's all fun and games, until Sonny Bill Williams punches you in the face.

Williams and Blues teammate Blake Gibson were filmed getting into a playful sparring session in the gym ahead of their clash against the Highlanders tonight.

However, as the two rugby stars were in the middle of their friendly fracas, Williams appears to land a punch right on his teammate's face.

The 32-year-old cross-code star posted the video on Twitter with the caption: "let's get it tonight brothers ... and yes obviously the uso Blake didn't want it today lol"

Williams, of course, has competed as a professional boxer, getting in the ring as recently as 2015 when he beat American Chauncy Welliver by unanimous decision.

The good news for Gibson - apart from probably having his life flash before his eyes for a brief moment - is that he was fine.

The Blues will be looking for their third win of the season tonight against the Highlanders at Eden Park.

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