So the first, smaller or easier action (opening the door a crack) makes the second, larger or more difficult action more likely.

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Nalbandian has slipped to 25th in the rankings this season, but after his shaky start in the opening set he became the first player to crack the Federer serve during the tournament.

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Mr. LARRY NOBEL (Former General Counsel, Federal Election Commission): If somebody sees a crack in the door, it's hard to stop them from opening it up.

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Opening their challenge in court, Gregory Jones QC also argued that "a crack" has appeared in the Department for Regional Development's case.

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