At the start of the season, Merson had said that Lukaku was inconsistent and Chelsea were correct to have sold him - as reported by Squawka.
However, the former Arsenal midfielder admits that he was totally wrong about the 22-year-old and he now believes Chelsea were crazy to have sold him.
"He’s changed my opinion, 100 per cent," Merson said. "I wasn’t his biggest fan and I thought it was the right move when Chelsea got rid of him.
"But he’s moved on, and he looks a much better player and they must be looking at Chelsea now, thinking ‘what did Mourinho did there’.
"He is an absolute handful. He works really hard for the team. He is winning me over.
"When you get it wrong, you have to hold your hands up and say you got it wrong."
Lukaku has been in wonderful form for Everton this season, and he scored his 19th goal of the season in Roberto Martinez’s side’s 2-1 victory over Manchester City in the Capital One Cup.
At the age of 22, Lukaku seems to have become the complete forward and he is developing a reputation as one of the most feared front men in the entirety of the Premier League.
The Belgian international’s pace and power has caused defences across England’s top tier no end of problems, and he has added a ruthless edge to his game.
The centre forward is winning more and more admirers by the week, and it seems that Everton could face a fight to keep hold of him, unless they can break into the European spots this season.