After Gold Glove third baseman Nolan Arenado made a nifty play on a hard one-hopper by Brandon Crawford to begin the eighth Sunday, Longoria followed by grounding a single past Arenado's dive.
The Giants had only one runner until Longoria's hit.
The 24-year-old Marquez is making his second start since signing a $43 million, five-year contract.
Colorado leads 4-0.
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