Borussia Dortmund revealed via their official Twitter account on Thursday that former Chelsea target Pierre-Emerick Aubameyang, who they could have signed for £70m in the summer, had been left out of the squad to face Stuttgart in the Bundesliga this weekend because of disciplinary reasons, which could leave his future in doubt.

What's the word, then?

Well, when a Dortmund fan asked the club on Twitter about Aubameyang's absence from the photos of the team departing for the trip to Stuttgart, he was told that the 28-year-old had been removed from the squad because of a disciplinary issue.

German media outlet Kicker believes that is continued poor punctuality is the reason behind the decision, and with the January transfer window just months away the rumours over his future are likely to ramp up in the coming days and months.

Chelsea were heavily linked with a move for the Gabon international during the summer before they signed Alvaro Morata from Real Madrid, with Sky Sports reporting in August that they were offered the chance to sign the centre-forward for £70m.

How has he done this season?

While his team have been below-par in the last six weeks – they drew twice with Apollon Limassol in the Champions League and have lost three of their last four Bundesliga matches – Aubameyang has once again been in brilliant goalscoring form.

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The 28-year-old has netted 15 goals in 17 appearances in all competitions, and he has scored 135 in 206 outings in total since joining Dortmund from Saint-Etienne in 2013.

Could Chelsea still be interested?

It's difficult to say.

While Blues boss Antonio Conte doesn't seem to be overly fond of Michy Batshuayi, with Morata as his undoubted first-choice striker it remains to be seen whether he has space for another unless he is prepared to play with two centre-forwards in the future.

The Italian has used a 3-5-1-1 system at times already this term though, and that would be easily transferred to two up top.

However, it would potentially leave key players like Eden Hazard and Pedro without a spot in the side or out of position, which makes the alteration a little less likely.

If Aubameyang does leave in January then he will want to be starting regularly and with that potentially not being the case with Chelsea – as well as a likely high price tag for someone that turns 29 next June – it could be a no-go deal for both parties.