He told liverpoolfc.tv: "I think he's a very good striker. He's also very young - 24 today. He can improve but is playing very well, so we're really pleased with him.
"It's (20 goals) always a fantastic achievement whether it's in the first, second or third season, but to do it in the first is really good for him because he's a new player who's had to settle down. I think he can continue improving and working hard, and that will be really good for the club."