Avoid your competitor's strength, and attack their weaknesses

Sun Tzu said “An army may be likened to water, for just as flowing water avoids the heights and hastens to the lowlands, so an army avoids strength and strikes weakness.”

Applying the principle to business competition: Many companies launch head-on, direct attacks against their competitors’ strongest point. But this approach to business strategy leads to battles of attrition, which end up being very costly for everyone involved. Instead one should focus on the competition's weakness, which maximizes your gains while minimizing the use of resources. This, by definition, increases profits.
(http://www.suntzu1.com/content/six_strategic_principles_for_managers/)