A method and an apparatus for preventing contention during the sequenced power up of an electronic system are disclosed. In one embodiment, the apparatus includes first and second power domains configured to receive power from first and second power sources, respectively. During a power up sequence, the first power source is configured to provide power prior to the second power source. A power detection circuit is configured to detect the presence of power from both of the first and second power sources. If power has not been detected from the second power source, a signal provided to a clamping circuit is asserted. When the signal is asserted by the power detection circuit, the clamping circuit may inhibit the control signal received from the second power domain from being provided to a power switch in the first power domain.