Bulldogs superstar Sonny Bill Williams says Andrew Johns is not the greatest player he has played against. The Kiwi second rower believes Johns should be made one of rugby league's Immortals, but rates former Sydney Roosters captain Brad Fittler as probably the toughest player he had ever come across on the football field along with forwards Gorden Tallis and Nathan Hindmarsh. "Joey Johns should definitely be made an Immortal, but I can't say he was the best player I ever played against," Williams wrote in his column for the ninemsn.com website. "Don't get me wrong, he was awesome and playing against him when he was on fire, like in the Anzac Test last year, he could be just about unstoppable. "I'd definitely have him in the top three or four, but I can't just rate him as the No.1 player I've faced in league because there are, and there have been, so many good players. "Maybe it's because I'm a forward and I watch and tend to pick out forwards as the hardest guys to play against. "I reckon the hardest guys to face along with Joey have been guys like Nathan Hindmarsh and Gorden Tallis, but the guy who probably sticks in my mind the most, and who would be right up there for the No.1 spot, would be Brad Fittler. "I'm sure it's partly because I faced up to Fittler in one game in particular in my first season and he absolutely hammered me. "I was watching (Fittler) on the other side of the park just screaming and rallying his troops around him all day and I was in total awe of him." Williams said he was disappointed Johns had retired this week as he was excited about playing alongside the 32-year-old in the All Golds clash in New Zealand at the end of the year. But his biggest regret won't be not playing with him, it is flattening the champion in round one this year. Williams floored Johns with a high tackle just four minutes into the game, leaving the halfback unconscious for two minutes and resulting in a send off for Williams and a one-week suspension. It was the last time Johns played in front of his beloved Newcastle fans. "I'll never get to play with him, but I'll be telling the grandkids that I played against him, but maybe not about the last game I played against him," said Williams. "I already felt bad after getting sent off against him in round one, and then I felt guilty all over again when I heard he was retiring. "Instead of being one of the last guys to play against him in one of his last games, I've got a memory I'd rather not have."