Swanson was backing out to avoid the hard punches early on. Stephens was firing away, hoping to land that big punch he was promising in the lead-up to this fight.
A missed uppercut was followed by an inside leg kick.
Finally, Swanson landed a body kick that hurt Stephens badly. We know this because he was actively backing away and trying to buy himself time to recover. Swanson rushed him and fired away with punch after punch. When he landed hard enough, Stephens decided to change levels and snag a single leg. That temporarily muted the blitzkrieg.
They separated and while Stephens was still alive, all the momentum had switched sides.
Once he regained the energy, Stephens pressed Swanson up against the fence and leaned on him. This may have been more for his benefit than Swanson's detriment. Referee Herb Dean demanded action, so they reset in the center.
From there, they exchanged punches until yet another stalemate against the cage.
That'show the round ended.