"It's uncomfortable," McCarthy said of Driver's condition. "We're proactive and sent him for some further testing."
Driver has caught at least one pass in 68 consecutive games for the Packers, the team's second longest streak behind Sterling Sharpe's 103 (1988-94).
If Driver and Ferguson, who is listed as doubtful on the team's injury report, are unable to play, the Packers will be down to three receivers – rookie Greg Jennings, Koren Robinson and inexperienced Ruvell Martin.
Green returns, ready to go
Ahman Green, who missed Wednesday and Thursday's practices, returned to participate today. He has been slowed by a sore hamstring, which prevented him from playing Monday against the Eagles.
If Green is unable to play, Vernand Morency would make his second consecutive start.
McCarthy said Green's sore hamstring may be a result of the quadriceps injury that he sustained last October. Green touched the ball (run and pass) 23 times against Chicago in Week 1, 22 times against New Orleans in Week 2, and 30 times against Detroit in Week 3.
"My experience when individuals come back from major injuries is you go through a period of nagging injuries," McCarthy said. "His is a tight hamstring that takes a while to get warmed up and fatigues over the long run. We're just being smart (by holding him out of practices)."
Coach pleased with progress of O-line
McCarthy said today that he plans to start Daryn Colledge at left guard and Jason Spitz at right guard in between tackles Chad Clifton and Mark Tauscher, and center Scott Wells on Sunday. Tony Moll, who started Monday against Philadelphia and gave way to Spitz likely will be used more as a backup tackle, McCarthy said.
"Tony has been moving around the line," McCarthy said. "Tackle is his natural position, so we feel like we're in much better shape than a couple of weeks ago."
Colledge, demoted to second string early in training camp, will be making his fourth straight start and appears to have entrenched himself at the left guard position. Colledge was replaced by Spitz in training camp with Moll at right guard, but after Spitz injured his hamstring in Week 1, Colledge got a second chance and has made the most of it.
"Daryn has done an excellent job of going from the situation he was in in training camp, fighting back," McCarthy said. "He's improved the last two weeks. I'm happy with the growth of the offensive line. You can see they're starting to get in sync. … That whole group is improving."