Mayfield completed nine of 16 passes for 138 yards during Thursday's preseason game in Detroit.
Mayfield played the entire first half and led the Browns to 17 points on five drives. He completed 35 of 61 passes (57.4 percent) for 501 yards (8.2 YPA) this preseason, with two touchdowns, an interception and 11 carries for 34 yards. Tyrod Taylor will get the Week 1 start, but Mayfield's solid work in August may leave the 29-year-old on a short leash.