The English, British, Commonwealth and European featherweight champion was ringside to watch Selby dominate Evgeny Gradovich for eight rounds before winning a technical decision.
While impressed with Selby’s performance, the Leeds fighter was more disappointed by Gradovich’s display and felt the Russian could have done a lot more in the fight.
“I expected a little bit more from Gradovich, I thought he was very one-dimensional, he just came forward in straight lines and he didn’t seem to have a plan B,” he said.
“For me, if you’re boxing for a world title, you put in absolutely everything to win that fight, but he didn’t change anything up.
“I’m taking nothing away from Lee, because he can only box who’s in front of him and he dealt with Gradovich very easily.”
Although most feel Selby proved himself a legitimate operator on the world stage, Warrington, who plans to return to the ring in September, came away with more assurance of his superiority over the Welshman.
“I 100% fancy my chances against Lee, even more so after seeing him on Saturday,” he said.
“I think he boxed very well, he won his title in style and I don’t want to p*** on his bonfire but I feel, being there ringside on Saturday, even more confident of doing a number on him.”
Selby has already spoken of his plan to make the first defence of his belt in Cardiff and Warrington concedes that it could be a while until he secures his shot at the new champion.
“I’d imagine that they will try and get Lee a couple of defences at home now, give him a few paydays,” he said.
“A fight with me I think can be built up and left to a later stage, I’ll leave it to Steve Wood [Warrington’s manager] and Eddie Hearn to get me the fights but it’s one that I desperately want.
“We’ll be looking at another year, maybe a couple of years before it happens. I’ve got to keep winning and he’s got to keep the title and we’ll go from there.”