Prior to arriving in Phoenix, the 1991 McLaren chassis had had only had one brief test session, and the two race cars were completed about 4 am Friday, six hours before the first practice session.
Antes de chegar a Phoenix, o chasis McLaren de 1991 só tivera unha breve sesión de proba, e os dous autos de carreiras completáronse ao redor das 4 a.m. do venres, seis horas antes da primeira sesión de práctica.