Nunez headed in from Robertson’s corner in Wednesday’s 3-0 Champions League win at Ajax to register his sixth Reds goal since joining them from Benfica in June.
That has come in a total of 13 appearances, with the 23-year-old forward part of the starting line-up in only seven of those games.
Asked about expectations on Nunez and comparisons with Haaland, who has continued his remarkable scoring record with 22 goals in 16 Manchester City starts following his summer move from Borussia Dortmund, Robertson said: “The only reason they’re getting compared is because they play the same position and they moved in the same window.
“Really it’s not fair on anyone – if it was vice versa, it wouldn’t be fair on Haaland either. It’s two incredible players, and we’re delighted to have Darwin here.
“He’s still young, which everyone forgets, and in front of goal he’s been really clinical, in terms of he’s maybe not played as many minutes, with the three-game ban and a couple of injuries.
“And he’s still adapting, but he’s getting there, and [on Wednesday] you could really see what his threats are.
“I think he caused Ajax a lot of problems and they were always worried about him, and he got his goal that he definitely deserved.”
The left-back added: “I think he has settled in really well. His English is getting better, he’s settled with his family and things like that, and that always helps off the pitch.
“And then on the pitch, I think he’s settling really well. His goal-to-minute ratio is very good.
“And you can see the problems he can cause, in behind and he’s a strong runner and he can be powerful in the air. He took his goal very well.”
Nunez scored shortly after the interval, to make it 2-0, having missed a good chance just before half-time, seeing his strike come back off a post.
And Robertson said: “He was really disappointed with himself at half-time, we had to kind of tell him not to beat himself up too much. But luckily he reacted really well and at the start of the second half he goes and gets his goal.
“It’s a big miss at the end of the first half, of course it is, but good strikers react.
“He was really disappointed, but he obviously used that disappointment to his advantage in terms of being angry and wanting to be in front of goal again, he didn’t shy away from that, and it was an unbelievable header and that’s what good strikers do.
“It’s a hell of a sign for him to bounce back from that, go again and get the goal he needed, and it certainly helped the team as well.”