The 6ft 6ins striker, who rose to prominence with four goals during Latics' memorable FA Cup run this season, hobbled out of last weekend's 1-0 defeat at Tranmere.
Scans on the injury revealed extensive bone bruising but no ligament damage.
Smith, 23, will still miss this weekend's npower League One home game with Bournemouth, Tuesday's re-arranged meeting against Hartlepool and possibly next Saturday's trip to Shrewsbury, with the Good Friday clash at Swindon set as a more realistic target.
