 Complete the following phrase:  Disagreement between the teams and the sports administrators over the technical regulations for the 1981 Formula One season contributed to Goodyears temporary withdrawal from Formula One and meant that the 1981 South African Grand Prix was run by the teams to 1980 regulations using cars with sliding skirts. Piquet finished second in a BT49B, but the race did not count towards the championship. The season proper opened with the 