- Belgian Grand Prix
- Andretti wins as the 79 is unleashed
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May 21, 1978: The much-discussed Lotus 79 was finally unleashed at Zolder and it made a winning start as Mario Andretti took his second win of the season at the Belgian Grand Prix to regain his lead in the drivers' championship
- Monaco Grand Prix
- Depailler finally wins to take championship lead
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May 7, 1978: Patrick Depailler scored his first grand prix win in style by winning the blue-ribbon race at Monaco after finishing second almost a dozen times in his previous 68 attempts