Chelsea anticipated Romelu Lukaku's return to Stamford Bridge with his Inter Milan form intact. The Belgian striker was one of Europe's most feared strikers, having played a key role in two consecutive Scudetti.

But that is no longer the case. After losing his starting spot in the Blues' line-up to Kai Havertz, the youngest foreign player to score 100 Premier League goals has looked like a shadow of the player who lit up the pitch for West Bromwich Albion, Everton, and, for a brief period, Manchester United when he first came to England.

Here are four reasons why Romelu Lukaku has struggled at Chelsea:

1. He's Short On Confidence:

Romelu Lukaku has had enough opportunities to look like his old self. But there have been times when he's looked like the Lukaku of his last stints at Old Trafford.

Mount, Ziyech, and Pulisic have all done their part at Chelsea, only for Lukaku to fail to make the decisive move towards the ball, find the requisite space, or break a gut to get into the box. We know he can do it since he's done it dozens of times before.

Strikers rely on confidence and solid habits in football since it is a game of momentum. Lukaku hasn't always had that momentum this season, which is why Havertz has got the nod ahead of him.

2. Lukaku Doesn't Look Happy In London:

The forward stated in a post-Christmas interview with Sky Italia that he was unhappy at Chelsea and wished to return to Inter before he became too old.

Lukaku's struggles this season may have been due to his inability to adjust to life off the pitch as well as on it. The Belgian was content in Milan and did not want to force a move, apparently preferring to stay at the San Siro. 

3. Chelsea Doesn't Appear To Be Playing To His Strengths:

Chelsea have been built up in an unusual way by Thomas Tuchel. Whether it's a wing-back or one of the wide players in the front three, the German has favoured goal threats cutting through diagonally during his tenure in London.

Lukaku's task for the European champions has at times just been to move out of the way of other attackers, although the Blues don't get many players forward anyhow. Havertz excels in the position of space invader; Lukaku does not.

4. Injury Woes:

Lukaku had a strong start to the season, bullying Arsenal in August and proving his worth when the weather grew cooler and Chelsea took control at the top.

But then he sprained his ankle and fell out of the side. When he returned to the team, the striker came off the bench to regain his fitness, only to be diagnosed with COVID-19