RIO DE JANEIRO—You might want to sit down, Bulls fans. Derrick Rose is sitting the Bulls’ preseason game Saturday against the Wizards in Rio because of left knee soreness.The team says it’s “precautionary.”  That left knee is of course the surgerically repaired one that Rose tore his ACL in during the 2012 playoffs and missed the entire 2012-13 season rehabilitating. Rose has appeared in both preseason games for the Bulls, looking a lot like his old self with explosive drives to the basket, but he played just 20 and 23 minutes in the two games. Rose declared in early September that he was “100 percent,” but he obviously might need to slow things down just a bit.It’s not unusual for Rose to be sitting since this is indeed a preseason game, but there is hyper-concern surrounding Rose’s knee, particularly because of all the time off he had last season. There were worries that he wasn’t healing properly or was experiencing complications or setbacks, but all the while the message was the same — Rose is fine, he’ll return when he’s ready.Again, the team is deeming this precautionary and it very well may be. Rose hasn’t played live NBA action since April of 2012 and with full contact practices and games, he might just need a little break. Let’s just hope that’s all it is. After this game, the Bulls return to Chicago and host Detroit Wednesday night at the United Center.