Rahman would fill the left back slot with Cesar Azpilicueta moving to right

Chelsea will be without right back Branislav Ivanovic for three weeks

Branislav Ivanovic expects to be out for three weeks with the hamstring injury he picked up on international duty.

Ivanovic returned to London at the weekend for scans after picking up the tear in his Serbia's 2-0 win over Albania on Thursday.

The absence of one of Jose Mourinho's key defensive stalwarts means £21million left back Baba Rahman could start against Aston Villa on Saturday.

Branislav Ivanovic (left) expects to be out for three weeks with the hamstring injury he picked up with Serbia

Ivanovic's injury means that Ghana defender Baba Rahman (left) could get his first-team chance with Chelsea

GAMES IVANOVIC COULD MISS 17/10 - Aston Villa (H, Premier League) 20/10 - Dynamo Kiev (A, Champions League) 24/10 - West Ham (A, Premier League) 27/10 - Stoke City (A, Capital One Cup) 31/10 - Liverpool (H, Premier League) Advertisement

That would see Cesar Azpilicueta revert to his natural role at right back in a Chelsea defence that has leaked 17 goals in the Barclays Premier League - the division's second-highest conceded total.

Ghana international Rahman, 21, arrived from Augsburg this summer but only has starts against Maccabi Tel Aviv and Walsall to his name since moving to Stamford Bridge.

Mourinho has so far resisted calls for the new signing to replace out-of-form Ivanovic in the side but his hand could be forced by his vice-captain's injury.

If Rahman does start against Aston Villa, Cesar Azpilicueta would move to his natural position at right back

Ivanovic has been part of a leaky defence but manager Jose Mourinho has elected not to drop his right back

When asked why he was not utilising Rahman earlier this month, the Portuguese coach said: 'Because Baba Rahman arrived in the last day, because he doesn't know what is is to play in this kind of championship.

'He had no pre-season with us. He needs time to learn, he needs time to adapt.

'If you don't have a minimum of five tall players good in the air, you are dead in set-pieces.

Rahman has just two starts to his name, coming against Maccabi Tel Aviv and Walsall, since moving

'When I play Azpilicueta on the right and Baba Rahman on the left and I don't play Ivanovic, I have only three, not ever four (players who are in the air). So we have to think about all the details. And I think about all the details.'