Caretaker coach Rob Howley described Robinson as "Shane-esque" ahead of their three-Test tour to Australia.
And Williams said: "He may be given a chance out there. He's different. He certainly works hard off the ball."
Former British and Irish Lion Williams, 35, bowed out of the sport on the losing side as he took to the field for the Barbarians.
But unlike in his official Test farewell when Wales lost to Australia in December or his last-gasp heroics for the Ospreys in their end-of-season Pro12 title win over Leinster in Dublin, Williams was this time not the star of the Welsh show.
WALES' JUNE MATCHES
Saturday, 2 June:
Wales 30-21 Barbarians (Millennium Stadium)
Saturday, 9 June:
Australia v Wales (Suncorp Stadium, Brisbane; 11:00 BST)
Tuesday, 12 June:
Brumbies v Wales (Canberra Stadium, Canberra; 10:30 BST)
Saturday, 16 June:
Australia v Wales (Etihad Stadium, Melbourne; 11:00 BST)
Saturday, 23 June:
Australia v Wales (Aussie Stadium, Sydney; 06:00 BST)
Robinson took that accolade with a blistering try that left opponent Williams expressing his admiration for the the Cardiff Blue, who is now a rival for North, 20, Cuthbert, 22, and versatile back-three star Leigh Halfpenny, 23.
Williams also praised Robinson's fellow debutants Liam Williams, at full-back, and fellow Scarlet, tight-head prop Rhodri Jones.
"They had a lot of youngsters playing and were under a little bit of pressure.
"Harry Robinson, I thought, had a great game.
"He started very well, scored that try and was very busy throughout and full credit to players like himself and Liam and Rhodri and these guys.
"They came in and played like they've been playing for 10 years.
"So I think that's what the game was about as well, blooding a few youngsters, trying a few players in new positions and, of course, they wanted to win that game.
"You're playing against some class opposition.
"It's never a structured game so it's a little bit more difficult.
"He's [Robinson] a little bit different to the likes of [Alex] Cuthbert and [George] North and… he had a great game and his confidence is through the roof and that's important."
Williams offered sympathy to former Ospreys team-mate, fly-half Dan Biggar, who
suffered a shoulder injury
before Howley announced he was among five players to be trimmed from the squad for the tour to Australia.
"He'll be gutted," Williams said of Biggar.
"He's played really well with the Ospreys this season, he had a bit of a rough time 12 months ago, not being selected for Wales and having stick sometimes off the supporters at the Ospreys.
"So it was difficult times for him.
"But credit to the way he's bounced back over the last 12 months. He's been fantastic for the Ospreys.
"Perhaps he feels he deserved the chance, really.
"But it's never easy and you do feel for Dan. But unfortunately there's competition for places."
That competition leads Williams to the conclusion that Wales can make history and win the Test series down under.
"I do believe they can win two Tests out there," said Williams.
"It's going to be tough, we know that, certainly, but they've got the strength in depth as well - that's what you need on tour."
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