A method for denying probes during proactive synchronization includes a first processor operating in an advanced synchronization mode, which includes the first processor specifying and acquiring exclusive access to a given memory resource. During operation in the advanced synchronization mode, specifying comprises executing a code sequence including: one or more locked memory reference instructions having a LOCK prefix and one or more addresses associated with the given memory resource. Specifying also includes executing an ACQUIRE instruction that is subsequent to the one or more locked memory reference instructions. The method further includes a second processor requesting access to the given memory resource and issuing a probe message. In response to receiving the probe message, the first processor responding to the probe message with a failure message, thereby denying the second processor access to the given memory resource.