Both sides fought through difficult conditions at the Stadio Sergio Lanfrachi with Keatley’s accuracy and a second-half try from Epalahame Faive proving decisive.
In a gruelling first period Zebre’s Marco Riccioni missed his first three penalties before finally scoring with his fourth to give his side a 3-0 half-time lead.
Faiva capitalised on a sustained period of pressure to score the first try of the game for Benetton on 53 minutes.
A conversion from Keatley and a subsequent penalty put Benetton in full control but Marco Manfredi bundled over for Zebre to set up an exciting finish.
The home side pushed hard but ultimately a further Keatley penalty proved enough for Benetton to maintain their dominant record over their rivals.
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