He did not participate in shootaround on Wednesday.
Durant experienced some cramping during Sunday's Game 1, a 121-109 win in which Durant finished with 32 points and 10 rebounds.
Warriors coach Steve Kerr said Durant didn't practice on Tuesday, noting, "If he didn't practice, there's concern."
Durant previously missed 19 games with a strained MCL and a bone bruise in his left leg.
In addition to Durant, Golden State guard Shaun Livingston (finger) and forward Matt Barnes (ankle sprain) are also listed as questionable.
The Blazers will continue to be without center Jusuf Nurkic, who is recovering from a right leg fracture.
Durant questionable for Game 2, expected to play in series
Warriors coach Steve Kerr discusses Kevin Durant's calf injury, saying the team will be careful and evaluate how Durant is feeling on Wednesday.