The 18-year-old scored two tries and set up another in Gloucester's 36-3 win at Kingsholm.
And his performance did little to lower excitement levels about the Wales Under-18 international ahead of this season's Guinness Six Nations Championship.
"International rugby is a big step up. The best of the best play there, and time will tell," Ackermann said.
"The first thing is for him to play well for Gloucester, and if he does get invited into the Wales group, they will compare him with what they have and then he has to prove himself.
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"He has definitely got the skill, but in international rugby everything is faster.
"He is good enough. He has got size, he's a young guy and he has got the mental toughness. It's just to get the formula right and the pathway right for him.
"I think it's great for him where he is in his career. He is young and playing good rugby.
"When you play a young player, you see a lot of good things in training and you hope he can transfer that onto the playing field.
"I didn't think he had all the opportunities in his first few games, and people didn't really see why we played him, but in the last two weeks he has started showing some of those things when he gets space.
"He is a confident guy. When you speak to him he is up to the challenge, he is engaging with his conversations and he has the confidence to try things on the field, and that's what you need at this level."
The 18-year-old now has four tries since making his Gloucester breakthrough (Getty)
Gloucester climbed to third place in the Premiership after sinking Worcester following a second-half scoring burst.
They made hard work of it for an hour, but four tries in 12 minutes forced the Warriors to surrender as Gloucester triumphed in bonus-point fashion.
Rees-Zammit apart, centre Chris Harris, flanker Ruan Ackermann and number eight Ben Morgan also touched down, with Danny Cipriani adding four conversions and a penalty to give Gloucester their first league victory since they defeated Wasps in late October.
Worcester were on the board first with a Duncan Weir penalty but conceded 36 unanswered points as Gloucester surged clear in the second half on the back of Rees-Zammit's excellence.
"We would have taken any result tonight," Johan Ackermann added. "The fact we got the five points is a plus. It was a tough game.
"You must work really hard to get your points against them (Worcester). Although it was 3-3 at half-time, we felt if we could be a bit more accurate, it would come."
Worcester rugby director Alan Solomons, meanwhile, had no complaints after seeing his side well beaten.
"We didn't have field position, we didn't have possession of the ball and all the points came in the last 20 minutes," he said.
"When you are stuck in your half and you are just defending, eventually it is going to lead to the other side scoring points, and that is exactly what happened.
"That is the price you pay for not having the field possession or the ball. We just tackled all night.
"You have got to give credit to Gloucester, they played really well. They hung on to the ball, and eventually the opportunities came for them."
PA
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