Gbamin made his first start for Everton in the win over Watford on 17 August
Everton have suffered a major injury setback as £25m summer signing Jean-Philippe Gbamin could face three months on the sidelines with a thigh injury.
The 23-year-old Ivory Coast midfielder, who signed from Mainz, featured in Everton's two opening league games.
But he missed Friday's 2-0 loss to Aston Villa after sustaining what the club described as a "significant" injury in training.
Toffees manager Marco Silva said "it is more significant than expected".
Speaking after the Villa defeat, he added it "will be some weeks".
Gbamin will have further tests this week and the worst-case scenario is 12 weeks out, although it is hoped there will be no need for surgery. Everton hope he will be back in two months.
Everton signed Gbamin and Fabian Delph to fill the gaps left by Idrissa Gueye - who moved to Paris St-Germain - and is it hoped England midfielder Delph, signed from Manchester City for £8m, will return imminently after a groin problem sustained in pre-season.
Source: bbc.com