The club stated on Friday that the Western Australian had received an MRI after reporting calf soreness, with scans confirming the extent of the injury.
Bombers General Manager of Performance Daniel McPherson claimed that while Guelfi had been a standout so far this summer, his fitness base will allow him to remain in the selection frame for Round 1.
“Matt suffered calf soreness following training and was sent for a precautionary MRI, which confirmed that he has a strain in his calf,” McPherson told Essendon Media.
“He is an important part of our team, and we will take the time to ensure he is fully recovered ahead of the season."
News of Guelfi's injury will have lengthened the face of Bombers fans, with the 24-year-old becoming the latest Don to hit a snag after Peter Wright (calf) and Elijah Tstatas (knee) were both forced from the track in recent weeks.
While Wright has already recommenced training at Tullamarine, Tsatas has joined fellow rookie Jayden Davey (knee) in the rehab group, with the talented teen having already undergone surgery to repair a torn meniscus.
The top-five draft choice is now expected to miss the next 8-10 weeks of preparation under new coach Brad Scott.
Guelfi enjoyed another solid season in 2022, averaging 13 touches and just shy of a goal a game from his 20 apperances.
Doing enough to impress, the bottle-blonde earned a fresh two-year contract in August, inking on with the Dons until the cessation of the 2024 season.
Essendon will tackle both Gold Coast (Austworld Centre Oval) and St Kilda (RSEA Park) in practice matches between February 23 and March 3 before opening their 2023 campaign against Hawthorn on Sunday, March 19 at the MCG.