Chelsea are considering a summer transfer bid for Bayern Munich star Thomas Muller as Diego Costa's future at the club falls into uncertainty, according to the Mirror.
Jose Mourinho is not planning to punish Costa for his controversial antics on the substitute's bench during Sunday's game against Tottenham, and will allow him to return to the starting line-up if he can impress in training this week.
However, there are concerns over Costa's state of mind in west London and there are already plans being put in place to find a successor should the Brazilian continue his descent. Their first port of call will be Muller.
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The 26-year-old has been one of the standout successes for both club and country and has continued his fine goal scoring form for Pep Guardiola's men this season. He has 13 goals in just 12 Bundesliga games and a further five in four Champions League appearances.
That is far more impressive than Costa's record this season. He has managed just four goals in 15 appearances and has inspired more headlines for his antagonistic behaviour on the pitch.
Unhappy in London
There are also rumours that Costa has failed to adapt to life in west London and was angling for a return to Atletico Madrid in the summer before eventually deciding to stay.
But it looks as though the situation is only going to get worse for the Spain international before it gets better and an exit from Stamford Bridge will be more than likely if he doesn't rediscover his goal-scoring form.
Chelsea face a formidable task convincing Bayern Munich to sell Muller. Manchester United have tried and failed to sign the Germany international in each of the last two summers but have found the Bavarian outfit unwilling to sell for any price.
Louis van Gaal reportedly offered £60m for Muller in the summer, but Muller is contracted to the Allianz Arena until 2019 and has so far showed no indication that he wants to leave the Bundesliga.