11:48 AM ET 10.21 | Denny Hamlin understands why NASCAR was so concerned about the hit he took during a crash earlier this week at Kansas Speedway. The accident -- Hamlin's Toyota tagged the wall while testing the speedway's newly repaved track Thursday -- left Hamlin feeling dizzy and disoriented. Hamlin was ruled OK by doctors and was cleared to race in Sunday's Hollywood Casino 400. But Hamlin's crash got NASCAR's attention, especially after Dale Earnhardt Jr.'s doctor advised him to sit out last week's race at Charlotte and this weekend at Kansas due to two concussions he'd recently sustained. So Hamlin has been hearing from NASCAR quite a bit over the last few days.