Cuthbert wasn't at his dominant best as Warren Gatland's men were beaten 21-16 at the Millennium Stadium, with the Blues star picking up a yellow card in the second half.
Yet the 24-year-old - who has made nine GUINNESS PRO12 appearances for Cardiff this season - has become a key figure in Wales' recent success.
And Hammett insists the British & Irish Lion will continue to work his hardest for both club and country.
"I had a seat behind the posts at the Millennium Stadium on Friday and from the view I had it looked like Cuthy worked really hard," Hammett told Wales Online.
"He went looking for the ball. The ball didn't always come his way and he would have been trying to get touches.
"But sometimes as a winger the ball doesn't get to you and it can look like you're not working hard.
"That's not the case with Alex. Whenever we have had him here he always works hard."
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