Sidwell came in for praise for his performance from Villa boss Gerard Houllier after replacing Petrov during the first half of Saturday's 1-0 reverse at Sunderland.
With Fabian Delph recovering from knee surgery and James Milner departed to Manchester City, Sidwell is the only experienced midfielder available to line up alongside Nigel Reo-Coker.
He has failed to hold down a regular first-team spot since his arrival from Chelsea two seasons ago.
But with Houllier unable to strengthen until January, the ex-Reading player will be in strong contention.
Houllier had initially hoped Petrov could be back in action within two to three weeks with his lateral ligament setback if it was a grade one injury.
But the ex-Liverpool boss conceded the Bulgarian international is likely to be out of action until the festive season or early in the new year.
Houllier confirmed: "Unfortunately I think we have lost Stiliyan Petrov for maybe at least two months.
"We will see if he needs an operation or not. We will know that by the middle of the week.
"It is a shame because he was getting up to a good level and he had got man of the match in the previous game against Chelsea."
Houllier has to decide who will skipper Villa in his absence and Reo-Coker will be a strong candidate.
He wore the armband during the Carling Cup third-round tie against Blackburn when Petrov was rested.
Reo-Coker has also had spells as skipper of the England Under-21s and West Ham, and Houllier spoke last week of the "trust" he has in the player since being brought back into the side.
If Sidwell gets the nod from Houllier, it will be a new-look central midfield combination.
Reo-Coker also had limited opportunities under Houllier's predecessor, Martin O'Neill, after a much-publicised training ground bust-up.