Arsenal have concerns over Kai Havertz's long-term fitness after his knee flared up on his recent return from injury - with the club forced to limit the striker's minutes to give him the best chance of playing a key role this season.
The 26-year-old suffered a knee injury in the Gunners’ opening game of the campaign, against Manchester United on August 17, and has not started a game since.
He had surgery a week later and, as Daily Mail Sport reported last month, in November the German was one week away from returning to a matchday squad before picking up an issue in his final training sessions.
It is now understood that Havertz had sustained ligament damage in the same knee he injured at Old Trafford – a devastating setback for the forward and one which led to another phase of rehab.
Late last month, the club posted a picture of Havertz training in the gym, following it a day later with a video of the forward training with his team-mates.
Yet, beneath the pictures and smiling warm-ups on the sidelines, sources say Havertz has been toiling away – and the battle is not yet over.
He is said to have again pushed himself hard in a bid to get back on the grass as soon as possible, with the support of the club's physio team, who have been very careful with the forward.
But Daily Mail Sport understands Havertz's knee has reacted again in recent weeks and, after being named in the squad for the first time since August for the win over Aston Villa on December 30, he was left out of the next two fixtures against Bournemouth and Liverpool to manage his workload.
Since being left out of the squad for the two Premier League games, the German has played 21 minutes in Arsenal’s FA Cup third-round tie against Portsmouth on January 11, as well as eight minutes in the Carabao Cup semi-final first leg win over Chelsea last Wednesday.
On Tuesday this week, Havertz stayed on the bench throughout Arsenal’s Champions League triumph against Inter Milan – to the surprise of many.
But Daily Mail Sport understands that Havertz was named on the bench against Villa earlier than expected and was still far from full fitness.
Given the setback that followed there are fears that if the knee continues to flare up, it could have long-term ramifications that could see the club forced to settle for prolonged management of his game time, rather than having him fully available for every match.
The Gunners are determined not to gamble on one of Mikel Arteta’s most trusted players and the process is being handled with caution.
He is expected to be given further minutes in the coming days and weeks, which will go some way towards assessing when the striker could be fully fit and consistently available to start matches for the rest of the season.
In his short cameo against Portsmouth, Havertz immediately looked confident, stretching defences and bringing others into play despite not being at 100 per cent.
For now, patience remains the priority.