Ashton Jeanty lowered his shoulder before giving Deommodore Lenoir a loud introduction to the strength and power that made Jeanty one of college football’s most prolific running backs and the sixth pick in April’s NFL draft. Lenoir, the San Francisco 49ers’ starting cornerback, tried single-handedly tackling the Las Vegas Raiders’ 5-foot-8, 208-pound rookie as he burst down the middle of the field. Instead, Jeanty pushed Lenoir down with his left hand and reached the 49ers’ 25-yard line before eventually being tackled by safety Ji’Ayir Brown on a 13-yard carry with 2:10 to go in the first quarter Saturday.