Rypien became the second stringer after Jay Schroeder, who had lost his job to Williams late in the 1987 season, was traded to the Los Angeles Raiders. In Week 4 against the newly relocated Phoenix Cardinals, Rypien got his first chance to start for an injured Williams and threw for 303 yards and two touchdowns in a 30-21 loss. In six starts, he went 3-3 and he appeared in nine games overall, including a four-touchdown game in a rematch against the Cardinals. He threw for 1,730 yards in those games and finished with three more touchdowns than Williams had, by a count of 18–15.