Daniel Wells and Michael Hibberd will need plenty to go right for the key recruits to be ready for the start of the AFL season.
Fairfax have reported that Wells will remain sidelined for Collingwood's last pre-season game this Saturday against Richmond in Moe.
And Melbourne have confirmed that a sore Achilles tendon will rule Hibberd out of Thursday's match against West Coast in Perth.
Wells has missed all three of Collingwood's pre-season games and given his well-documented history of lower leg injuries, he will need a lot to go right to be ready for round one.
Hibberd has played in the pre-season, but a teammate stomped on his Achilles last Friday at training.
A key issue for the backman is he missed all of last season because of his Essendon doping ban.
Like Collingwood with Wells, Melbourne will be conservative with Hibberd's return - especially given it is the start of the season.
Hibberd is among several current and former Essendon players who are nursing injuries as they return from their 2016 bans.
Port Adelaide's Angus Monfries has a shoulder injury, while Essendon's Cale Hooker is close to resuming from a hamstring injury.
Hooker's teammate Michael Hurley hurt an ankle late last month against Gold Coast, but the Bombers are confident he will play in Sunday's match against Geelong.