Another Lions injury worry after fullback Kinghorn limps off
The Scottish star, widely seen as starter in the first Test against Australia, was limping heavily after an awkward landing early in their 36-24 win and was replaced by Marcus Smith.
Coach Andy Farrell said "hopefully it is not too serious".
"He said someone landed on his knee, he was walking around," he added to Sky Sports immediately after the match.
It is another blow for the Lions who have already lost versatile English utility back Elliot Daly to a broken arm and experienced Welsh scrum-half Tomos Williams to a pulled hamstring.