Here is a good Dimaond level match between Psy and Qwerty. They are playing as Zerg and Protoss. Psy playing as the Zerg goes for a fast expand and builds three Spine Crawlers for defense. The Protoss goes for a four gate early game push with Zealots and Stalkers.

The Zerg meets him with lots of Zerglings while teching to Hydralisks and is able to hold him off. The Protoss keeps up the pressure but Psy is able to find his Proxy Plyon where he is warping in units and destroy it. This is what happens when Zerg is able to get an expansion early and hold it.