Many--perhaps most--articles about health savings accounts suggest that employees with an HSA who participate in a 401(k) plan should first contribute to the 401(k) plan the percentage of their compensation that enables them to obtain the maximum plan sponsor match, such as 3% on the employee's first 6% of compensation. Employees should then max out their HSA account contributions through payroll deductions. Once that's done, they should go back to contributing any additional dollars to their 401(k) plans.
While this strategy is indeed attractive, an even better one would be to change the sequence of the contributions. That is, employees should first max out contributions to their HSAs no matter their tax bracket, and once that's done, contribute to their 401(k) plans.