Of course, Zhou Tian could have directly destroyed the Dragon Rider with the situation at the time. But clearly, the Dragon Rider wouldn't just allow Zhou Tian to take him out like that. As a result, even under Zhou Tian's attack, the Dragon Rider was far from idle.
Just as Zhou Tian was about to wipe out the Dragon Rider, after having been suppressed by him, the Dragon Rider finally struck back against Zhou Tian, unable to bear his onslaught any longer.
There was a reason the goblins created Dragon Riders instead of giant dragons. According to the goblin's design, the seemingly unresponsive knight was an integral component of this weapon. Its importance was not overshadowed by the dragon, and synergistically they were more impactful. As such, when the knight riding the Metallic Giant Dragon started to exert his power, Zhou Tian quickly felt the pressure.