It's happened again.

Chicago Bulls star Derrick Rose landed awkwardly on his left leg and went down holding his left knee and had to be helped off the court.

The injury happened with 90 seconds of the Bulls' Game 1 battle with the Philadelphia 76ers. Chicago was up 12 at the time, and once again basketball fans will question the wisdom of Bulls' head coach Tom Thibodeau.

Rose has had a long list of injuries this season, as he has missed 27 games with toe, ankle, groin and back injuries at various times.

Rose looked like he was back to his dominant best—or at least close to it—as he was close to posting a career-first playoff triple-double with 23 points, nine rebounds and nine assists.

Rose's latest injury did not look season-ending but perhaps series-ending as his left knee twisted inwards on landing. Whether it is mild (a sprain) or severe (a ligament tear needing surgery) will be determined by an MRI scan either tonight or tomorrow morning.

Despite the huge playoff win, the United Center atmosphere was more akin to a funeral as Bulls fans looked on in fear as their one great championship hope was helped back to the locker room.