Belgium international Romelu Lukaku said he has evolved since he last played in the Premier League two years ago and has returned to Chelsea as a more complete player.
The 28-year-old striker moved to Chelsea from Inter Milan last week for a reported sum of £97.5million, earning him a second spell at the London club where he spent three seasons from 2011 to 2014.
"I just feel more complete. I've tried to master all the facets that a striker needs and I just want to keep improving on the small details all the time," Lukaku told the club's website.
Lukaku was Inter Milan's top scorer - with 24 goals - in Serie A last season, leading them to their first Scudetto in 11 years.
"Italy is tactically and technically a better league but here in England, it's all about the intensity... but it's no problem for me because I've been here for eight years..." he said.
After leaving Chelsea, Lukaku switched to Everton before signing for Manchester United in a big-money move in 2017 that ended in disappointment. Criticised for his levels of fitness and lack of finesse, the striker left Old Trafford after just two seasons.
Lukaku, however, insisted that he has no "unfinished business" in England.
He said: "I don't really talk about my personal ambitions but they lean with the club's ambitions. That's why I came back... I'm a new version of that player from before."
Lukaku added that he likes manager Thomas Tuchel's system and is prepared to adapt.
"I can play as a two or by myself and I'm used to the system because it's what we play with the Belgian national team."
Lukaku was unavailable for Chelsea's 3-0 win against Crystal Palace over the weekend but is expected to feature against Arsenal on Sunday