1. catch someone off guard - to surprise someone by doing something that he or she was not expecting.
2. cave in - give in or agree to something that you previously did not want to accept.
3. come up short - means to try to achieve something but fail, but not completely. E.g. "The charity fund raiser was supposed to raise 1 million dollars, but came up short.
4. corner a market - dominate a particular market. E.g. "Apple has corned the market on cell phones. They have a large % of market share.
5. cut corners - take a shortcut; find an easier and cheaper way to do something. E.g. "Our company doesn't cut corners on our luxury products".