The Bomber missed Round 3's clash against St Kilda after experiencing soreness, with subsequent scans confirming the injury.
Essendon's GM of Performance Daniel McPherson confirmed that the 25-year-old could be on the sidelines for up to two months.
“'Guelf' has a high-grade hamstring injury that we'll take a really conservative approach with,” McPherson said.
“He won't do much for the next couple of weeks before commencing some running – he's likely to miss six-eight weeks.”
Meanwhile, Brandon Zerk-Thatcher is looming as a possible inclusion for Round 4's clash against GWS as he continues his recovery from an ankle injury, as is Anthony McDonald-Tipungwuti, who hasn't featured since Round 1 due to a quad concern.
"‘Thatch' has progressed well over the weekend. The plan will be for him to complete some modified training over the next couple of days, before having him train fully on Friday and then be available for selection,” McPherson said.
“We also expect ‘Walla' to train fully this week and be available to play on the weekend.”
Defender Kaine Baldwin has also been added to the injury list after suffering a delayed concussion after a head knock in the VFL, now sidelined for the mandatory 12 day period.
‘Balders' got a cut to the head in the VFL,” McPherson said.
“He was assessed for concussion and was cleared to finish the match but then developed symptoms later Sunday night and Monday morning. Further assessment indicated he was suffering delayed concussion, so he won't play this week.”