Dan Connolly, who left Sunday's win over the Titans with what was reported as a "head injury," suffered a concussion, but its effects were mild enough to hold out hope for a short absence, says a source. The Patriots right guard appeared to take a shot to the head when tight end Rob Gronkowski landed on Connolly during a second half touchdown plunge by Stevan Ridley. Connolly didn't return to the game after that and did undergo sideline testing during the game, according to Greg Bedard in The Boston Globe.Any player exhibiting signs of concussion is not allowed to re-enter a game or practice on the same day. The NFL does not have independent neurologists on its sidelines during games despite a swell of support for that measure. Late last season, independent trainers began being positioned in press boxes to monitor forhits or behaviors that looked ominous in terms of head injury. Connolly missed two games in 2010 with a concussion. When Connolly is completely asymptomatic, he would be allowed to return. It will likely take most of the week to determine whether Connolly will be available for Sunday's game against the Cardinals, but the early hope is that the concussion was not at all severe. Donald Thomas took over in Connolly's absence Sunday.