He won the 1978 South African Grand Prix, with a last-lap victory over Patrick Depailler, as well as the Austrian Grand Prix, in the innovative 'ground effect' Lotus 79. His teammate Mario Andretti won the Drivers' Championship with Peterson acting effectively as the Team "No. 2" with the pair scoring four 1–2 wins, all with Andretti at the lead. Both of Peterson's wins occurred when Andretti encountered trouble, with Andretti winning once when Peterson failed to finish (not including the Italian Grand Prix). Many times, Peterson followed Andretti closely home, leading to speculation that 'Team Orders' were in place.