Boston Celtics All-Star point guard Isaiah Thomas received a platelet-rich plasma injection Wednesday for a groin strain and is likely to miss his second straight game on Friday against the Toronto Raptors, according to Celtics president of basketball operations Danny Ainge. During his weekly appearance on Boston sports radio 98.5 the Sports Hub, Ainge deemed Thomas day-to-day but hinted the team would exercise caution before putting him back on the floor. Thomas, who injured his groin during the first half of Monday's loss to the Houston Rockets, flew back to Boston on Tuesday and missed Boston's 117-87 triumph in Orlando on Wednesday night. Thomas had the injection into a thigh muscle, Ainge told the "Toucher and Rich" program. "I think that it's just day-to-day. I mean, he is a warrior. He loves to play. He'll be back faster than most players would be back after an injury. "At the same time, we really have to be careful with Isaiah for the long haul...