Manchester City overcame a spirited Middlesbrough side to maintain Roberto Mancini's unblemished record and book a place in the FA Cup fourth round.
Benjani broke the deadlock on the stroke of half-time when he swept home an incisive pass from Martin Petrov.
Boro impressed with their work-rate and commitment, but struggled to create.
Their attacking play improved after the break, however, with Rhys Williams heading over their best chance as City squandered several opportunities.
The win maintains City's flawless start under new Mancini, who has now guided his side to three wins in three games, with six goals scored and none conceded.
But while Mancini might have racked up 10 Coppa Italia wins as a player and manager, his team selection will have left some onlookers questioning his determination to build on that notable cup record in England.
Adopting a conservative approach, the Italian made five changes to the City line-up, leaving Benjani to plough a lone furrow up front and handing young defender Dedryck Boyata a first-team debut.
Even with City in fine form since he replaced Mark Hughes, it was a risky call by Mancini and on another day it might have backfired.
Boro, labouring 26 places below City on the league ladder, had won just twice in 10 games since Gordon Strachan's late-October arrival on Teesside.
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Scunthorpe Utd. 1-0 Barnsley
1-0 P. Hayes 68.min.
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Blackpool 1-2 Ipswich T.
0-1 J. Colback 3.min.
1-1 B. Ormerod 51.min.
1-2 O. Garvan 77.min.
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