New West Bromwich Albion signings Joleon Lescott and Sabastien Pocognoli were both injured in their pre-season defeat to Nottingham Forest on Saturday.
Lescott was withdrawn after initially being brought on as a half-time substitute, while his teammate was taken off late on.
The centre-back lasted just over 30 minutes before he was substituted, and referee Andre Marriner also succumbed to injury and was replaced after seven minutes.
New Baggies manager Alan Irvine told Sky Sports News: "[It's] not a big problem by the looks of things, but I was concerned early on as Joleon did come off very quickly.
"He's had a bit of a problem with the outside of his knee and he said that it had settled down.
"We'll assess him and hopefully, he'll be training during the week."
Lescott arrived at The Hawthorns from Manchester City earlier this summer.