Prince Harry neglected to mention his cancer-stricken father when he popped up at a glamourous American football award ceremony.
The Duke of Sussex turned up to present the NFL Walter Payton Man of the Year award.
The Prince made a series of jokes comparing rugby to American football at the speech in Las Vegas, Nevada.
The award ceremony comes ahead of this year's Super Bowl, which is being held in Sin City this weekend.
Prince Harry made a surprise appearance at the award ceremony
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It is believed the Duke flew to Vegas just 24 hours after landing in LA following a 11,000-mile round trip to London to see King Charles for 45 minutes.
Speaking at the event, Prince Harry joked that: "You stole rugby from us and you made it your own...Instead of passing it backwards, just pass it forwards. Why not wear pads and a helmet?
"Of course, have an offence and defence, that makes sense, and why not have a breather every 15 seconds? And you know what? Instead of a 10-month season, let's just make it 18 weeks. Genius.
"All kidding aside, what you guys do on and off the field is truly remarkable. You are role models for millions in the way you carry yourselves and the way you give back.
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Prince Harry with NFL Walter Payton Man of the Year Cameron Heyward and comedian Keegan-Michael Key
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"This final award, the highest honour, is all about serving your community, and there is one special man we'd like to pay tribute to now."
Harry was not expected to be seen in public again until he travels with wife Meghan Markle to Canada next week for an Invictus Games event.
However, he shocked the audience as he turned up to hand out the award.
The award, which is presented annually to a player who has made a commitment to philanthropy and community impact, was given to Pittsburgh Steelers defensive tackle Cameron Heyward.
Prince Harry giving the award
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Heyward said: "Prince freakin Harry, I'm just shocked, that's Prince Harry."
Prince Harry flew into London on a 10-hour flight from Los Angeles on Tuesday and arrived at the royal residence at 2.42pm before spending around 45 minutes with King Charles.
His brief return to the UK has caused controversy among royal fans. One dubbed him "traitorous little toe rag."
Another called said they were more hopeful of a royal return for Harry, saying he and William should "step up" in the King’s absence.