Romelu Lukaku has described his first spell at Chelsea as "painful", but he insists the experience helped him improve as a player and is confident the timing of his return to Stamford Bridge could not be better.

The Belgium striker joined the Blues from Anderlecht in 2011 as a teenager, but played just 159 Premier League minutes in his first season before loans to West Brom and Everton in the next two campaigns, eventually joining the latter on a permanent basis in 2014.

A further three years on Merseyside were followed by stints at Manchester United and Inter, before Lukaku returned to Chelsea this season.

He has four goals in all competitions so far this term, at least twice as many as any team-mate, from a team-high 25 shots. Left-back Marcos Alonso is next on that list, with 17.

Lukaku has actually marginally underperformed compared to his expected goals total of 4.15, yet he has brought more than goals alone, creating 15 chances – this time just behind leader Alonso (18).

The 28-year-old believes that his time in London played a significant part in his development.

"[My first spell at Chelsea] was painful and helpful, but I would say more helpful because it gave me the mentality and the mindset that I needed to become the player I am today," Lukaku said.

"The team was very good, but nobody saw the extra work they did after the training sessions. As an 18-year-old, I saw first-hand every day how much the players worked on their craft.

"That’s when I knew that was what you had to do to become this type of player. I told myself, 'when I’m not playing, this is what I'm going to do', and it basically just became a lifestyle."

Lukaku is no longer the raw teenager that arrived in England 10 years ago, now back at Chelsea as a seasoned, world-class centre-forward who was a key part of the Inter side that wrested the Serie A title from Juventus last term, scoring every 120 minutes in the league.

He was linked with a return to Stamford Bridge from Everton in 2017, but instead joined United while Chelsea signed Alvaro Morata. However, Lukaku is certain the circumstances of this move are perfect.

"I knew I would improve as a player, so it was just about timing," Lukaku added. "I had two opportunities to come back, in 2016 and 2017, but it didn’t happen for various reasons.

"In the end, it happened because now is the right time, the right age, the team is doing well and everything is there for it to be successful.

"I’m much more calm. I've matured with fatherhood, and I’m more laid-back. After winning in Italy and knowing what it takes to get there, that really helped me. In the last three years, I’ve been able to build something that I can take on for the rest of my career.

"It can be complicated but when you really set your mind to do something, and you really dedicate everything that you have to that goal, you can achieve it. I recognised my little qualities and talent, but I also knew what I was not good at, and I really spent a lot of time working on those attributes to be the complete package.

"Now, it feels good. I'm very happy with the opportunity, and we've started really well as a team. My team-mates have made life very easy for me and the coach is doing a great job. Our performances have been good, but we're always looking for the next challenge."