Nash said it's an injury that has been bothering the 32-year-old Harden for several days, but after Saturday's game, the coach left open the chance that he might play.
"We'll have to see how it settles, but we're hopeful," Nash said when asked about Harden's availability for Tuesday's tilt at the Phoenix Suns.
Harden's latest injury comes as a surprise given that Nash said he went through all of Friday's practice and was ready to play again after missing Wednesday's loss to the Denver Nuggets because of left hamstring tightness. Harden had the MRI in San Francisco on Saturday after waking up with discomfort.
"Clean of the bad stuff, but a strain for sure," Nash said of the MRI. "There's stuff on the MRI, so he's feeling something, feeling the strain. It's been bothering him, but he was like, 'Yeah, it's nothing.' Now it's a little more than nothing. He woke up with a marked difference in the hand."
Nash said Harden doesn't remember a specific activity when the injury occurred just that it has been bothering him for "a few days."
"He doesn't remember an event," Nash said. "But the scan shows the irritation, the strain, and he has said he's had it for a number of days, so I think the deduction would be that he must have irritated it shooting and lifting [Friday]."
The Nets are already playing without star forward Kevin Durant, who suffered a sprained left MCL in his left knee during a Jan. 15 win over the New Orleans Pelicans. Durant is expected to be out at least a few more weeks as he continues the rehab process.
Aside from Harden's injury, the Nets suffered another setback when big man LaMarcus Aldridge sprained his left ankle in the fourth quarter against the Warriors and did not return. Aldridge used crutches as he went to get checked out after the game and ultimately left Chase Center in a walking boot.
"I think he tweaked his ankle, but I'm not sure how bad it is," Nash said.