Sonny Bill Williams shows off his impressive vocals in post-op video

He's shown his star qualities in both rugby codes and tried his hand at boxing, but it seems Sonny Bill Williams' talents are not confined to the sporting arena.

On Monday night, Williams posted a video on Instagram from his hospital bed following keyhole surgery to repair the knee injury which has ruled him out of the All Blacks test series against France.

The 32-year-old asks nearby nurses for any particular song requests, then launches into a rendition of 90s pop group All-4-One's chart-topper I Swear, which garners a number of mixed reactions.

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Williams added a disclaimer with the footage, which he posted to Twitter.

"Okay team - here it is. I just want to reiterate again that the meds they give you for surgery are very strong and take a while to wear off... but I also feel like the staff took advantage of me (I'm joking). Thanks to the nurses/staff for putting up with me haha!"

SBW adds a couple more tidbits, admitting his appreciation for former One Direction member Niall Horan.

"I love Niall ... he's the man. He loves rugby," said Williams.

SBW is scheduled to be sidelined for four weeks as he recovers from the procedure.

This article was first published on NZ Herald and is republished here with permission.