Mauricio Pochettino admitted he is concerned by Christopher Nkunku’s ongoing injury absence with Chelsea’s attacking options looking stretched ahead of Saturday’s meeting with Fulham.

The France international returned from a five-month lay-off following knee surgery only in December but has missed the team’s last two fixtures with a hip issue.

He has been unable to train since before Chelsea’s FA Cup win over Preston on January 6 and the manager said he is unsure when Nkunku, who was the Bundesliga’s top scorer last season with 16 goals for RB Leipzig before moving to west London for £52million, will be available again.

With fellow summer-signing Nicolas Jackson away representing Senegal at the Africa Cup of Nations for what is likely to be at least the rest of the month, and Armando Broja still looking to find form after being sidelined for nine months with an ACL injury, Pochettino has few options in Nkunku’s absence.

Chelsea’s goalscoring form has improved significantly on last season, when their return of 38 was the club’s lowest in the league for almost a century.

They currently have 34 at the halfway stage of the Premier League campaign, but despite this they have repeatedly found it difficult to break teams down, and have failed to convert high possession figures into   clear chances.

They enjoyed 72 per cent of the ball and had 18 shots on goal during Tuesday’s Carabao Cup semi-final first leg away to Middlesbrough, yet still slumped to a 1-0 defeat at the Riverside.

“I’m a little bit worried because I don’t have the whole information (on Nkunku’s injury),” said Pochettino. “If he’s going to be ready or not, or available (after) a short period.

“We need to be very clinical and, if it’s possible, to take some decision. If not, we need to think about how we can fix the problem.”

The 26-year-old shone during the team’s pre-season tour of the United States before injuring his knee in a game against Borussia Dortmund in Chicago.

That sent early plans for Pochettino, who had hoped to use Nkunku as the focal point of his side’s new-look attack, into disarray, and heaped pressure on Jackson and Broja – both only 22 – to take up the goalscoring mantel.

The club have been linked with possible moves for Brentford’s Ivan Toney and Brighton’s Evan Ferguson in January to help bolster their attack.

“(Nkunku) was the only player that was performing, of course in a different league, in Germany,” said Pochettino. “But consistently scoring goals. That was the situation before the start of the season.

“When (the injury) happened, we needed to see about Broja after one year (out injured), and Jackson moving from Villarreal, where he wasn’t top scorer.

“The age of the players, (they are) young guys that need to adapt. That was why we felt a little bit more the hit of (losing) Nkunku.

“He was consistently scoring goals. When you miss a player like this, you hope that players that maybe came here and need time to grow and score goals, it (became) a necessity, compulsory for Jackson to score in every single touch.

“Or Broja, after one year out, needs now to play three games in a row. It’s difficult for him.

“It makes our job more difficult. It’s exciting this project, but situations like this make it more difficult. You have to grow at a different pace.”