Nicolas Jackson has provided a cryptic injury update ahead of Chelsea's clash against Copenhagen in the first leg of the UEFA Conference League round of 16. The 23-year-old striker suffered a hamstring problem during the Blues' 2-1 win over West Ham last month, and he's been out of action ever since.

Jackson, who sees his contract at Stamford Bridge expire in June 2033, has featured 23 times in the Premier League this season, scoring nine goals and providing five assists. Before picking up the muscle injury, he played a key role in Enzo Maresca's side, and he fired Chelsea into the top four.

The West Londoners have dropped to fifth in the Senegal international's absence. Jackson, who enjoyed a brilliant start to the campaign, was not thought to have suffered a major knock, only for a scan to later reveal a much bigger problem.

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Speaking to reporters last month, Maresca confirmed that the striker won't return until after the March international break. The Chelsea boss said: "We knew it was a muscular problem but not how important it was.

"His reaction was good so we didn’t think it was a big injury. Unfortunately, he had the scan and it is an important one – he will be out for six to eight weeks."

While Jackson's not expected to return from the sidelines until the end of this month, he appears to have been making good progress on his road to recovery. On Monday night, the Senegalese star posted a selfie from the gym at Cobham training ground to his Instagram story.

As pictured above, Jackson was kitted out in his Chelsea gear beside a squat rack. Last month, Maresca heaped praise on the frontman after the Blues crashed out of the FA Cup to Brighton.

"Sometimes I think you need to play some games without players to realise how important they are," said the Blues boss. "Off the ball, his pressing is always very good and on the ball he is a threat always.

"We started very good, controlled and created some chances. The second half more or less happened the same. If there is something good after a defeat is now we can be focused on the Premier League and Conference."

Christopher Nkunku has covered for Jackson, and Maresca wants to see more from the Frenchman. The Chelsea head coach said: "I’m happy with him, I know that he can give more. We expect more from him.

"At the same time we try to understand him in terms of he is not a nine. Many games he plays as a nine. He’s not a winger and tonight he played as a winger.

"He’s an attacking midfielder. The problem is that sometimes to find balance… we already used Cole Palmer there so we try to use him in different positions."